If you have a 3GS or older (or no iPhone at all) go for it - it's not a bad phone, just not the upgrade 4 owners (including myself) were hoping for. If you have a 4, then it's upto you. I thought about it for a while, and although I was initially against it, I decided to get it because:
A) I could use 64GB
B) I could sell my (unlocked/jailbroken) 4 for profit