Since I mention Playchess in another review I made here I guess I ought to let you know my opinions on Playchess aswell? First: Playchess is Thomas Stahl - it seems to be him only. his is for good and bad. It sometimes is obvious that he spends a lot of time developing the site - good - but at the same time misses up on maintaingn the one that is running - bad. Cheating.
Well, since Playchess provides games against humans aswell as against computers the risk of spending your time playing against a computer without knowing it is smaller than on gameknot. At least that is how it feels to me. The players at Playchess seem to be honest players too. Thomas Stahl seems to try to stop the cheaters when they are exposed, which is very good for the honest players.
Also I think that the tournaments at Playchess have a lot positive for the players. The bad things are however obvious: There are not many players compared with other similar sites. That makes it hard to find opponents that you can have a good and equal game against. You often after some time get to play either with newbies who are just too bad for you or old members that play like gods. With a clubrating of say 1750 you soon get fed up.
Also - Playchess is not for free. If you want to be a guest - listen to this - you have to pay for it. Innovative yes, but since that makes you forced to pay a full year in order to see if it is for you, then there is not much point in entering at the first time.
OK, you CAN join a free test account 3 months. But since Playchess uses the Fisher time counting you never get the time to finish a tournament until your test period is over. So if you want to play - pay. I cant recommend you to pay for this, not as long as there are free services available - like FICS and others - and since other subscription services like ICC are much better. Sorry - but as long as Playchess cant offer something better for the money I cant recommend it.