If you've played Xbox Live, you should know that voice chat is a must. When you're playing a team game, you want to be able to talk to your team mates. If you have a team in Halo 2 that doesn't talk, you aren't going to win. If you have a team that talks and plans things out, you have a much higher chance. There are the annoying people, which is countered with a mute option. Click on the person's name, press A on mute, no more annoyance! You can also go into the setting and just turn voice output off, or take your headset off. FDV, online games have the "Game experience may change during online play." disclaimer because of how people can act online.
If Rev's online is anything like the DS's though, it's going to be very lackluster. I was playing Mario Kart DS yesterday and kept getting in games with people snaking the entire match. I just wanted to race some people that, you know... didn't snake. I guess I'm just spoiled by Xbox Live, but I was really missing my "Avoid player" option, the feedback system, or just some way to tell the person I didn't enjoy playing with them.
With the DS, there's no way for Nintendo to get feedback on the players and ban the cheaters, exploiters, and just plain *******es.
gg Nintendo.