ChessWorld full membership costs $28.50 US dollars or 22.5 EU Euros or 20 GB Pounds. Free membership offers quite limited access to site benefits but if all you want to do is play chess then lack of other benefits really doesn't matter. They offer only correspondence chess with no variants. Tournament play offered consists of thematic, team and league events, round robin (all-play-all), knockout and pyramids. You can also play individual games if you desire by accepting challenges or issuing your own. They also offer a pretty nice Homepage where you can post all kinds of stuff about yourself or anything you are interested in. You have to be a full member though if you want your picture posted on your home page.
What I liked about the site was that I could set my own initial rating and so avoid having to slog through a hundred games against low rated players just to get decent competition. You will play a game against a “welcomer” who will be rated near your rating and who will be willing to answer any questions.
Well moderated forums consist of chess, book reviews, openings, etc. Also great fun if you are so inclined is the social forum where you can chat with players from all over the world but unfortunately that's a full membership forum. Full membership offers you a wealth of resources to improve your game…much of it contributed by members. Because the site is located in England, they often have member meet ups so a lot of the players are well known to each and many are FIDE rated with lots of OTB experience.
If I had to pay for a site this would be the one. In fact I did pay to play there for six years before discovering Queen Alice where I can get decent competition for free. Five stars for this site!