Ok, what I learned for those looking for a bit of a head start.....
Spy: A lot of people seem to trust medics running backwards =p What I mean is, he can disguise himself as any class and appear as a member of the opposite team which even fools sentries. But the best way to get past the enemie's "front lines" is using the stealth ability, since nobody trusts a blue heavy running past the red team to join the blue team mid fight. Then once through the lines you can find yourself a nice secluded spot to reappear and run out. They can cause engineers some headaches by sapping/destroying their sentries or you can find lone players and backstab them for insta-death. But regardless your style this class is a lot of fun to play and makes you feel so evil muahaha....
Engineer: Great in close combat with shotgun and for closed in spaces with sentries... but in wide open areas he sucks because the sentries have pretty short range on their targeting and shotgun loses to rocket launch in the open. In addition to the sentries he provides some important support abilities in the Dispenser which provides healing to anyone teammate in need of it. And of course he can place the teleport start/end points which speed your team up tremendously when attacking a long distance away or when they have to run through some dangerous areas to get to the good defense points.
Heavy: Combine a heavy with a good medic who can provide invulnerability and you have a very deadly combo. He is stupid slow when firing but death awaits anyone who ends up in the path of the bullets...provided he is somewhat close to them. He also has a metric F-ton of health so he can take a beating.
Sniper: Having to wait for the insta-kill shot to charge is somewhat annoying if you are used to other sniper weapons, but ultimately its a good balance that prevents shooting from the hip. There are some pretty good sniper spots if you know what to look for and the sniper is easily countered with spies who just backstab the bastards. All in all you can rack up some pretty good kills with this guy if you know what you are doing and have the aim for it.
I didn't spend any time playing the scout, medic, soldier, pyro, or demo guy yet. Saving those for tomorrow. I probably missed a class but oh well, I am tired and I am heading to bed.
Right now I think the respawn timer is way too long, 20 seconds seems to be the norm and honestly being out of the action that long just sucks.








