I played quite a bit after it went live; I was a very regular player for probably a year and a half after that, while I was in school. Since then, I've more or less given it up. I re-sub for a month and check it out once or twice a year, but at this point I don't think I'm going back.
It was a phenomenal waste of time. Fun, but an absolutely pit to pour time down. I think my total time played would probably amount to a thousand hours or more, and what do I have to show for it? Some pixels on the screen, and a few fond memories. I gave it up, and also gave up TV, and with the time it's freed up, I've been able to read all kinds of books, keep up-to-date on the news, and even start learning a couple of new, real-life skills. I'm always a little tempted to go back--but not tempted enough to give up my free time.