I had to have a chance to play the game myself though to have a final opinion. I played through all 3 races once each time. The game has a very different feel, of course I've seen a ton of Sc2 games on huskystarcraft so I already knew most of the units and abilities. The hotkeys I notice are very different like for marines. M queues up marines in Sc1 but in Sc2 you use A. These small hot key changes were very strange when I played the first time. Auto mine also felt surreal. Above all, the most relieving difference is how you can hot key more than 1 building to a hot key. It felt amazing being in such powerful control. I kept on forgetting you had 2 vespene gas, and when you queue up an addon for a Terran building, it automatically starts making it and unlike in Sc1, you don't have to select where you want to place your building with the addon. I still haven't tried out most of the abilities, but I was pretty amazed by the Mules, supply drops, scans, the marauder, the Thor, the everything. You can also queue up several buildings for 1 unit to build. It was all amazing. Also, when you command an scv or probe to build something, if you try to have it build something else, the worker unit will treat it as 2 buildings for it to queue. Walling in is a relief, and everything feels so different. Simply put, I love the game! I can imagine it all. Storm drops. Rushing High Templar. Doing cool marine drops with medivacs. Going mass Immortal. I never realized Immortals cost so much, but they're more than worth it. You gotta go those Guardians, slam it out with some cool Warp Gates, burrowed moving Roaches with regen, and most of all, burrowed banelings. Right now I'm in love with the Protoss the most, but I will have to try out each race more to see what I have the fun with most.
Sc2, great game, still haven't tried any new HotS units or abilities, but still a great game. It convinces me I must have this game! I don't think I'll play through the single player campaign and just go to the multiplayer. Of course, it is likely my computer will only be able to play on the lowest settings.
Edit: Does anyone know how to do save location hotkeys? Feels strange without them