I love PBP. For me it's been far more rewarding than any table-top game I've played. Mind you, I was a little younger when I last played face-to-face, but PBP brought me back to gaming and D&D.
I've played some fantastic games over the years. Sure, I had a load that died as well, but I've got three fairly committed groups that I play with. Our Age of Worms game has been going for 4 years now - we're just over half way. Yes, it's slow but the RP and interaction, and detail in the story make it more than worth. Combat is not as bad as most folk make it out to be. You can finish a normal encounter at 1 round per day, easy.
Our Shackled City game is now 3 years old - We're about 1/3 in and it's been one of the best games ever for me. I've been in PBP for almost 8 years now, and I wouldn't play D&D any other way.
Yes, it's slow, and yes combat can take long, but with a good group where people have the time to post 1-3 times per day, which is what we've got, you just can't beat it. Perhaps it's rare to find a good group.
Anywho, I find it very rewarding - it's the only way I play at the moment, and it suits my lifestyle as it doesn't nearly take up some much time each week as a face-to-face session would. The OOC banter is great as well - in fact, I've ment gamers in our group from Asia and the USA and I live in the UK.
So, just wanted to say it's worth it. Don't give up on one or even a handful of bad experiences, and keep in touch with the players you get on with so you can form a good group. I've been gaming with the same players for through different game for 5+ years now, the longest being almost 8 years.
Pinotage