I don't think it's a bad strategy at all - I used to play exclusively like this, and still stick to it, but have found that switching it up in certain ways helps.
PF I always raise the same amount (unless say there are several limpers, then I'll raise the pot) but like Arbakov said, the size of your bet may hint your opponents as to the strength of your hand.
I raise 3.5 or 4 bbs every time, so that opponents are left guessing as to whether or not it's a steal or a real hand.
though I like to mix it up in tournaments, as the people there won't be seated with you too long, so it's useless to try to bet like that.
Once in a while I'll also pull limp-raises, and mix it up a little at cash games if i feel the table is too loose, or if i have a certain read on an opponent.
I think this kind of play works well with observant players, but at the low limits and micros that most play, it's next to useless when you're playing against someone who really doesn't care about your betting patterns.