I enjoy it, and the dev team has been very vocal about fixing a lot of the major gripes in the game (see recent news posts
http://na.apb.com/en).
I've spent a good day or so in the game, and I'm not bored of it. There's so much stuff to unlock and customize what whatnot that I can't see it being boring for a while. It's a solely PvP game, so unlike WoW there's no "go kill some AI wolfs for 20 hours", which is what I consider the boring part of MMOs.
I don't know many other people who have the game, so I don't play it so much, since you REALLY need to play it with someone you know, since most people who hop on alone aren't so great.