I played SC2 many hours every day at DH Winter 09, nov 26-29.
I played almost only Terran.
I think that the game was really really great and i long alot for the beta to be launched. However i was a bit disappointed by how the terrans worked. The infantry is really strong. Actually i went a build with 2 pretty early barracks, one with tech lab and one with reactor, making marauders from one, and marines from one. when i had about 8-10 marines and 3-4 marauders i would attack the protoss. I did not fail once with this build, however i realize that it is probably defendable if you rly see it coming pretty early. But as i said i didnt lose once.
I also tried quick hellions for harassment vs both protoss and zerg. Against protoss it worked sometimes, depending on whether the toss had gotten a stalker yet or not. But vs zerg it didnt rly work since all good zergs had already gotten hydralisks (although hellions are better vs hydra than vulture is vs hydra if you tank with infantry since hellions do lots of dmg vs hydras while vultures do not).
I also tried rushing reapers with stim and d-8 charges vs zerg. It was LOL. could not lose. i could get 4-6 reapers and win with them. The only way the zerg could defend was if the had rly good micro vs the charges or 2+ spine crawlers. Even if the zerg had 10+ hydras and 10+ lings i could easily stim up a cliff, drop 6 charges in the zerg minerallines, blow up 90% of the drones, snipe the remaining 10%. and get out with losing at most 2-4 reapers. (reapers cost 75/50 and builds fast).
And basicly marauders and marines with medivacs late took both zerg and toss, with some assistance from mech or air units.
However almost every time i skipped rax units and went straight for factory units i lost (and not because i was run over b4 i had gotten an army). I tried mass rush hellions. i tried tankwall&turret push. i tried thor/tank, thor/hellion, tank/hellion. i tried macro games with tank/turret def and i tried games with dual armorys for quick upps. but i almost always lost. I also know about 10 other ppl who played alot every day who said the exact same thing. We discussed ways around this but we always came to the same conclusion. However of course there is dropcheeses with hellions and stuff that would work on occasion, or if you simply were a better player, or did something they didnt see coming etc etc.
Oh btw currently in TvT its mass air until someone succeeds in getting exansions and resources for thors and its gg. (banshee -> vikings -> thors -> win. Since banshee pwns tanks, hellions and barracks units.)
I tried alot more than these tactics but i dont feel like writing down the details of every single game and the small differences between them.
My point is that infantry is the base of every terran game besides tvt atm. Factory units are great for support but a mech army vs toss or zerg like in SC1 is a lose strategy.
This is however just mine and the other ppl i played with at dreamhacks experiences and that we only played the game for 3 days. I also would like to say that i am not worried though as i believe that everything will be fixed during the beta testing period.
Finally i would like to say that i wrote this to give the community some info about the current state of the game, but also to show people why Blizzard is postponing the game so much; they simply want to ensure that the game is flawless when they release it. Last but not least, the game in general was fkin awesome. I was happy to find out that many of the bad rumors of the gameplay was simply just rumors, and even though i was one of those ppl who thought the game would be completely awesome, i was extremely positively surprised.
Dont hesitate do ask something about the game or this topic, and i already know that i write long sentances with many commas.