My friends and I have begun playing this game every thursday on a server we set up and speaking over our own teamspeak-like server (mumble) so we can keep trash talk internal.
Since the skill level of most of my buddies ranges from average to below-average, I tend to stick to classes I am not as confident with. I've gotten both the sniper and pyro to levels that I am very comfortable with so the next class I wanted to focus on is the spy.
He is slowly becoming one of my favorite classes. It will be challenging to master him, but I am having fun trying.
Currently I am really enjoying the knife called "Your Eternal Reward." It is a knife that disables your disguise kit. The only way to disguise yourself is to backstab someone. But the benefit is that you instantly change into the person and the kill is a 100% silent kill. The victim makes no noise. Leaves no body. And the enemy team doesn't even see the killscore show up on their screen.
I was on a ctf map this weekend (turbine I think) and the enemy had three engineers and three sentry guns in the intel room. I had stolen a disguise at the front of their base and walked through the ductwork. Each engineer was banging away at their guns, wary of things but not entirely keeping a close eye on each others' backs. I dropped down into the room and just like in a movie or batman arkham asylum, I took out the first engineer silently. Since the disguise change is instant, the sentry guns don't even make a responding peep. I walked over and took out the second engineer silently. The third one, still oblivious to what was going on, wasn't as easy to get to. So I sapped the first two sentry guns and his distraction was enough to expose his back to me. A moment later he was joining his friends waiting to respawn, and all three guns were taken out.
Oh, and if anyone here wants to join us on thursdays you are more than welcome. We usually start around 7pm Mountain (9pm Eastern).