Fluidity alike none other. SC2 delivers anything one could ask for!
Thankfully, Blizzard is not retarded. They replaced units and made everything right. If you are missing Medics so much just go play singleplayer. Tons of units are in singleplayer that are not in multiplayer.
Singleplayer- Long, lots of variation, packed with cinematics both pre-rendered and real time rendered. The story is what keeps you playing. Blizzard has always been good at turning the stories found only in books and movies into interactive adventures. The relationships will keep you going back.
Multiplayer- Much better than StarCraft was upon release. It is nearly balanced completely and plays very, very, nicely. Tons of little "easy mode" features have been added such as auto mining, range indicators, ergonomical hotkeys, and my favorite- unit path finding. No longer do units run around aimlessly after finding obstructions. If units block the path, they step aside to let a passerby go through. The new ranking system is great for keeping fair fights and it's always fun to play the unranked matches and roflstomp noobs with friends.
There are many minor issues that are being addressed. Lack of chat rooms is already going to be fixed. Lan will most likely never be seen thanks to the pirates. The new outweighs the old. Having friends lists, party chats, and other social features bring out the WoW style of social interaction at every corner. You can even bring up friends lists in game and chat or broadcast to all friends.
Ultimately this game is amazing. Buying it should be a no brainer. After all, aren't all 100million dollar games great?