I have played in the 4545 League for almost four years and been a team captain most of the time. I have played a lot of serious and interesting games against different opponents (including Smyslov_Fan who was so impolite to publish his win against me here in the forum

- see the recent Chigorin thread in the d4 d5 section).
I can generally confirm was S_F already wrote - and let me add a few more comments:
- I don't think computer cheating is a serious problem. During my tourneys one of my opponents was later expelled for cheating (which was quite annoying, since I had actually been the only one to defeat him). When playing over the games afterwards with an engine switched on, I find the usual bunch of errors and inaccuracies you could expect from human players at my rating level. Generally I think the computer cheating problem at ICC is overrated, and at least I think the risk of meeting a cheater is low when you play organized tournaments like this.
- S_F says that players know a lot of theory and use a lot of book. Yes, and in addition they may be well prepared for you - at least after a while, since the entire history of league games is kept and can be downloaded and studied. See that as a challenge, not as a problem - and prepare for your opponents yourself.
- The is a tournament that takes itself seriously. There are detailed formal rules, which are enforced quite rigidly (sometimes too rigidly in my opinion). If you don't show up for a scheduled game there is no mercy - the game is lost and no matter your excuse, you get a "reliability rating reduction", which may decrease the number of sections you are allowed to play - and in the end may get you suspended from the next tourney.
- To be eligible to play, you must have played at least 20 standard games on ICC. For the first tourney, you are eligible for playing in one section. A you behave well, this number may increase up to three sections.
- The teams consist of 4-6 players, and in each round 4 players play. So if you are in a team with 4 players, you have to play all rounds. If there are more players on the team, you will normally be able to sit out if needed, but you cannot be sure. When the team lineups are published, you have one week to schedule and play the game - in most, but not all, rounds, you are however allowed to adjourn the game up to one week.
- The players paired are often from very different time zones (typically American vs. European players), so you should be ready to play during weekends. If you are generally not able to play during weekends, the league is simply not for you.
- The maximum rating rules for the teams are applied strictly. This means that players often may have to leave their teams and find new teams. This is annoying, but is has the advantage that the teams to some degree are reshuffled - and it may provide new league players some better chances to find teams.
- And a final important point: the next tourney closes for entries in six days from now, on April 15. So hurry up to find a team.
- The league website is
http://team4545league.org/, where a lot of info can be found (e.g. about how to join the league). There is a similar league for FICS
http://teamleague.org/. These two leagues were "married" until a few years ago, when the "divorced" (quite peacefully and friendly, as far as I know).
(And BTW I am currently looking for a 6th player for my U2000 team. The player should have a rating of 1890-1910, not much outside that. I anyone is interested, let my know very soon).