This is the only forum that I've been to where nobody has posted a topic about how X-Box Live has been royally fucking up for the past month.
It's hard to connect to it, you generally have to try about five times, however once you do establish a connection, certain games have their own flaws. For example, CvS2 makes it almost impossible to start a game without it disconnecting, you just have to get lucky. The ranking system is fucked up as well...
It's hard to connect to games in Mech Assault from the lobby, however, once you do get into a room, it's usually ok. Once the match ends though, it won't let you stay in that same room, it just loses the connection (and yes, the game is supposed to let you do that now since they released a patch).
I've also heard that some games (I remember Rainbow Six being one of them) show the player lists as empty, when there really are more players on the server.
There's also been a few reports of some friends lists getting fucked up randomly (people getting deleted, etc).
Calling Microsoft's tech support doesn't do shit either apparently. First you have to bitch at them and tell them that the problem isn't your ISP, router/hub, or whatever, and that it's their problem and that about 10000 other people are having the same difficulties. Then they still just deny that there is any problem with their service, even after you talk to the "supervisor" or whoever the hell is supposed to have some high-ranking authority over there.
Microsoft can shove it.
I don't really go to many forums anymore, but from what I've seen, GameFaqs (a hell-hole, yes, but I checked it anyway), Shoryuken.com and Snk-Capcom.com all have reports of this.
Edit: I forgot to mention that I'm posting in this topic because Ghost-Dog mentioned that there are a lack of people on Live... I should probably make a new topic for this, but I'm too damn lazy.

I'll just let someone else handle it.