I'll buy it when there are some worthwhile games. I think it depends how close its release date is with BF4. I've been really craving a BF console game with 64 players, and I might buy a PS4 just for that. There'll also be GTA V to consider as well, but they might be games I simply purchase for the PS3. It remains to be seen.
Once the bugs get worked out on it, and the price comes down a little more. The price now is really tempting though . But I want to make sure that if there's anything wrong with it, I won't get stuck with a lemon. It's an investment.