1. The variety of game play experiences derived from the heroes alone rivals moba games, and that is a very positive thing. Every match will be a little different, because you'll very rarely have identical teams to previous games on both sides, at least in pubs. I'm a little more worried about competitive, since the most recent major had C9 coalesce to a lineup of 2 Winstons, 2 Tracers, and 2 Lucios regularly towards the end of matches. This may indicate an emphasis towards characters with increased movement, since in Overwatch that effectively means reduced cool down time when you factor in time to arrival at the objectives. Blizzard should seriously look into how this affects team compositions at the highest levels and potential ways to compensate, like giving Tracer and Lucio slightly increased respawn timers for instance.
2. Each character feels unique. This is a concern that I see voiced often, that people who aren't necessarily fans of mobas, or people who are fans of TF2 constantly gripe about. There need not be any overlap among heroes, and as soon as there is, the game will feel superfluous or cheapened. Currently, that is not an issue. There are few enough heroes such that they were able to design drastically different skill sets for each one, yet there are enough heroes such that a small soft-counter dynamic is allowed to manifest itself. Some heroes are better against certain heroes than others.This is healthy, and will lead to dynamic matches where there is a lot of character switching, a design decision that Blizzard seems locked in on for better or worse. I'm personally glad that character switching exists, because lineup losses are a real thing in mobas and are generally boring for players and spectators alike.
3. Here's a list of heroes that I found to be the most fun, and they will be the first heroes that I play on May 3rd when open beta comes around for those of us who pre-ordered: Junkrat, Road Hog, Pharah, Winston, Widowmaker, and Symmetra.
Junkrat's skill set is just awesome. His primary is a skill shot with a high ceiling, his shift is a fantastic movement ability and a high damage nuke, his snare is a decent stun albeit hard to land, and his ult can wreck if you're sneaky with it. It's too bad he's not seen in more competitive games and I hope he gets buffed at some point in the future.
Road Hog also fits into the "fantastic skillset but underrepresented in competitive" box. A hook is essentially a guaranteed kill on any non-tank hero. This seems great. He's got an incredible self heal that allows him to front line, but which doesn't offer protection to his team like a Reinhardt or Winston shield. I hope Blizzard buffs him slightly, for instance, giving allied health regeneration after using his self heal in a small area, or something. His ult also isn't as game changing as a Winston ult, for example, because of the lack of maneuverability. You'll secure a kill if you're lucky while everyone hides and lock down a capture point for 5 seconds. This seems underpowered compared to Reinhardt, who will definitely secure multiple kills if he hits multiple people with his ult, or Winston who just eats supports and non-tracer squishy characters during his.
Pharah is everything that I wanted Soldier to be in TF2. Her jump jets plus jetpack allow her to both escape danger and setup kills, and her knockback can be great in tight situations against tanks. Her biggest downsides are map-specific: in some maps she just won't have room to fly around and there aren't open enough spaces for her to abuse her rockets, because there are too many corridors to hide in. Still, she's competitive open parts of the maps and ridiculously fun.
Winston is obviously a high tier front liner. His health and dps are through the roof, and coupled with his charge and bubble he's the king of capturing objectives. His ult essentially gives him free reign over whatever space he currently occupies, which goes a long way towards winning escort maps. He's easy to play right out of the gate and scales well as you learn what to do.
Widowmaker, as the sniper, occupies an important role that in other shooters often feels pigeon-holed and rigid. Widowmaker does not suffer that characteristic. Besides sniping, which is her most important role, her ult also provides distinct tactical advantage for the entire team in giving everyone wall hacks for a short duration. I see Widowmaker's ult as an FPS parallel to Mirana's ult in Dota 2, for instance: the entire team benefits from a temporary period of extreme tactical advantage. I think this is great from a design point of view: she'll obviously be popular because people love to get headshots, so make her ult something that everyone gets to benefit from. Well done Blizzard!
Finally there's Symmetra, who is easily my favorite support. She seems like a one-trick pony when you first play her: build up to teleporter, place it somewhere that's not stupid, and watch your team build advantage during drawn out fights due to the shorter effective respawn time. The reason why Winston / Tracer / Lucio is so popular is that they fill all the roles nicely, for one, but also that they allow quick returns to the objective point after deaths. Symmetra with a well placed and well guarded teleporter fills that role single handedly. But she also has a high damage, shield piercing nuke in her primary fire, which is something that is unique among all heroes as far as I know. She doesn't care about Reinhardt or Winston shields at all. Her turrets are also extremely powerful, and often netted me multiple kills before the opposing team caught on and took them out.
4. Besides the heroes, the three maps that I got to play on were well designed. They offered a dynamic array of environments as games progressed. I could have played another 50 hours on just those three maps and been perfectly content with the variety offered. The fact that there are 9 more that I haven't even seen yet fills me with anticipation. I can't wait for May 3rd!
5. Finally, I have a couple suggested improvements. Constructive criticism, if you will.
a. First, give us some control over the maps we play. A veto system would be great. In fact, add this to heroes of the storm as well. If it worked for SC2, why not for the rest of your games? This would also give a good indication of which maps may need tweaking based on their popularity.
b. Add more to the score screen at the end. I want to know how many kills and assists I got, as well as the amount of heroes that took my teleporter, how much damage my sentries did, how much damage I tanked or healed compared to everyone else. Give me the percentage of hooks landed, rockets that dealt damage, number of ults used. Basic statistics for every player, which can be referenced in retrospect to gauge improvement. This seems so basic to me for a competitive game that I'm surprised I need to speak up and ask for it. The more information, the better.
c. Maybe add more distinct team colors so that it's easier to distinguish between friendly and enemy particle effects. It doesn't need to be too overboard, but there were a couple times when multiple heroes occupied slots on both teams that it got rather confusing who was who. The effects that are already in place are almost there but they need a little tweaking for accentuation under certain circumstances.
Overall it was a great experience. Blizzard bottled lightning and channeled magic for this title. I haven't been this blown away by a Blizzard game since vanilla wow in 2004. This might be their game of the decade, and I can't wait to play hundreds more hours of it.