I have an inactive paid account. The pre Cat patch was just plain broken. Lots of crashes. I did not like what happened to ret, and raiding stopped because people were getting bored/not used to new talents and PvP was terrible. Even the last rush to get achievements before Cat was difficult because as soon as I got summoned to Ulduar my PC crashed and wouldn't stop crashing as soon as I logged in.
Fast foward a few months and Cat came out, I did eventually buy it for $20, and gave it a go, I didn't really get that into it. Ret was slightly less broken, but the game just wasn't as enjoyable for me anymore, and still constantly crashed. I lost interest for six months and didn't really think much of it, but did still keep in touch with some people that played WoW. Anyway, F2P came out, I thought I'd give it a go for nostalgia's sake, and much to my surprise did find that I enjoyed it, and am still playing a few months later, although I must admit, not nearly as enthusiastically as I was to begin with.
As for paying in the future, I got a seven day trial recently and just wasn't into 85 content at all. I made a DK to support my F2P and that's pretty much all I did on the paid account. I do have a TCG pet. I didn't personally pay for it, someone gave it to me. There are things I'd consider paying for if it was worth it to me, but I'm not interested in World of Kung Fu Pandacraft, or anything currently on offer.