Terran
Battle Hellions:
I like the unit, its a melee tank with ok overall damage that will deal with light units efficiently. Also it has micro potential with its differing roles when transformed (to harass or run away). So not totally an A-move unit like the Warhound. I am hearing it is still light tagged while in battle mode and that is something I dont agree with. If they are supposed to function as meat-shields they should be able to tank baneling damage. As they are they have weakness to anything non light such as roaches, spines and even the new queens. Even light units like hydra's will do well agianst them because of their new speed and much longer range as shown in the TvZ battle report. Having further weakness to banelings is too much IMO especially since the unit with its slow speed does not have the splinting potential of marines with stim to avoid some damage from baneling splash. Hellions, when transformed should be tagged only as mechanical in my opinion. Just like they were at blizzcon.
Warhound:
solid, mass-able unit. With good stats, price, HP and efficient supply count. The mech marauder some call it and perhaps it is for the better, since blizzard is intent on keeping siege tank's role to a minimum and further diminishing the unit with HOTS. This unit has little micro potential but I am fine with that, considering every other terran unit is micro-based already.
Widow Mines:
The only original addition and an actual creative unit to the terran arsenal. Its a solid unit that helps both bio and mech but more so mech. This unit will be a solid early-game anti-Air option for terran mech that was sorely lacking in WoL which weakened some mech openings beyond viability. Especially in TvP.The mine can be used to counter voidray openings from protoss, banshee openings from Terran and early muta openings from zerg. A welcome change from being forced to rush armoury and thors or mass turrets because you opened mech.
I am also hopeful that this unit might provide some answers to terran late game air options as well against late game Z units. I can see spider mine flanks on broodlord/corrupter/infester armies that are engaging terran armies, which as off now are too cost efficiently for the zerg's side. Especially after the removal of the ghost's viability in that match-up with the snipe nerf.
Solid and original addition. The timer on it might be too log as many have said. 5-7 seconds should be more skill intensive on the part of the opponent.
Reaper:
I don't think this unit will be more viable in HOTS compared to WoL. Reaper speed and building attack are removed in exchange for Combat drugs, 10 more HP and 5 second build time reduction. Not enough to make the unit viable especially with the queen buff, as it was demonstrated in the TvZ battle report.
They need their speed back as an upgrade or base line with these changes.
Other Terran Units:
Ravens:
For the love of god improve or replace this unit blizzard. The raven is too expensive, the spells too lack-luster and the upgrades/buildtime/Tech-lab-req too intrusive. There is a reason the unit is scarcely built after 2 years of game play, even less than units like hydra's. This unit is supposed to be terran's T3 spell-caster which is equivalent to infesters and Ht's.... The meta-game will not save this unit blizzard, YOU must.
I would suggest removing seeker missiles and improving ravens other spells. For example making auto-turrets a potential base defence function by removing their expiry limit, perhaps with a HP reduction to the turret. Pdd is a fine spell as is, it would be neat if it had additional function of stopping units from being dropped under its radius. For third spell I would suggest adding the mech sci vessel heal ability or something along the lines of the current sensor tower (with the structure being removed). since ravens are usually built with mech units those spells will be more helpful than the current spells and would make the unit worth the current cost, build-time and make them a viable T3 support caster.
Thors:
I am disappointed this unit still has energy in the recent Hots build (it didn't have energy in the battle report build). It seems it will transfer its weakness from Wol to Hots unlike Ultra's that are improved and the ever powerful colossi. It fits the theme with Terran T3 being much weaker than other races and it seems this weakness will still exist in Heart of the swarm.
I would suggest making thor's AA more viable and more effective vs all air unit types in exchange for reduced ground attack damage. Also remove the energy please, either by replacing their canon upgrade, putting the spell on a Cool-Down or removing the spell altogether.
BattleCruiser:
I like the red-line reactor addition. I think 100 energy is too much though. 75 is better and introduces a viable energy dump against Ht's.
Zerg
Viper:
Good unit, lots of micro potential and interesting game play. its pull spell is currenly 7 range which I think balances it against air units unlike many folks have complained. I do think one of its spells need to be researched however, it should not come with 3 powerful spells as default (non of the other T3 casters do).
I am sad that this unit further weakens siege tank use in HOTS. Perhaps the pull ability should not work on deployed/pinned units like borrowed/sieged/wrap-prism deploy. I disagree with folks suggesting a T3 restriction on the pulling spell, that's the unit's main use and attraction.
125 energy balances it's other spell blinding cloud. like I said though either this spell or abduction need a research requirement.
Swarm Hosts:
Interesting unit, I have heard both positive and negative things about its new implementation. My suggestion? make it a ground centric siege unit as it was in blizzcon, locusts attacking both air and ground seem gimmicky, unrealistic and difficult to balance.
Ultra Charge:
Too powerful in my opinion, if ultra's need help (which I don't think they do, with their use increasing massively in tournaments) it should be addressed in a different fashion. Like the often suggested push mechanic against zerglings.
From what I hear when ultra's charge they will do friendly splash as well as enemy splash when emerging from ground. That might be something blizzard is trying to balance them with. Still I don't like it.
I am afraid blizzard has invested too much of a "wow" factor in this ability for zergs--with whole slew of new animations, physics and video hype-- that they will try to keep it regardless of balance. Might be wrong though.
Protoss
Tempest:
Lots of complaints about this unit so far and its extreme range, at first I was very much with that mindset as well until I saw David kims interview on their purpose. Now I am more open to the idea of tempests and their extreme rage and the new options it would introduce into the game.. if not 22 something less perhaps. Tempest build time right now is 75sec, which is extremely short compared to carriers (120 sec) with similar costs. However they are units designed for harass more than right on mass-able combat units. They will force enemy to change builds and get sky units to counter them. On the downside they are weak in direct combat with low dps as well. I can live with this unit and its extreme range, though perhaps a-little less than it is right now (15-20 maybe).
Oracle:
The unit from blizzcon, the building/tech stun spell is gone for a new temporary cloaking ability. I like this change since the building stun seemed OP. The unit it self is fast, can harass and can support the death-ball with cloak... I like its harassment spell entombed. I dont like duration of Preordain however.2 minutes of vision around a building or unit(not sure) with 13 range on the vision... 2 minutes seems like scan on steroids to me and abit too long. 30 seconds sounds more balanced. Also I agree with Avilo on its cloaking ability requiring a T3 structured, perhaps the fleet beacon. otherwise I foresee cloak gateway timings combo with preordain for detection will be a problem for Zergs and terrans.
Mother-ship Core:
Broken as it is. Specificity the energy recharge spell is broken. For 25 core energy you can recharge back nexus energy to 100.. in other-words almost endless chrono energy on nexus (which would be equal too endless mules on an orbital). Also it buffs units to full energy as well. its kaydarim amulet and much more. This spell is broken and needs to be removed IMO. The temporary canon seems powerful as well if it requires no tech buildings other than a nexus and 100 min 50 gas to get a core (as it is right now). It should require tech buildings to activate otherwise every protoss will be opening nexus first and will still be full-proof to any rushes. The teleport is one of its spells that can be balanced considering it costs 150 energy.
I haven't seen to much on the mother-ship itself that upgrades from the core other than the vortex spell is replaced with a stasis spell. I like it. Tempest replaces vortex as the Anti-Broodlord weapon for protoss.
Excuse the potential grammar & spellings mistakes.