I would opt to not buy the phone if my only option, due to budget, was a 4. I'm not being snobby. I'd talk to some people who have the 4, but I think you'll find that as they age (they're, what, three year old technology now?) you're going to be able to do less and less and less with them. Faster processing and better software on the new iPhones will mean you can't update your operating system, you can't update or download apps. To me, I wouldn't take the $200 gamble on it and I love, love LOVE my iPhone. I have a 4s (which would be a far better choice, if you can make it). In fact, I love it so much and it works so well, dh and I haven't opted to upgrade yet even though we could have.
Additionally the time will come a lot sooner when Apple stops supporting the 4. For instance, the first gen iPads are no longer being supported and I don't think they were released much earlier than the iPhone 4. That's something to consider.
What's so great about iPhones? Dh is a techie, so I'll just use his words. The phone just works. Apple has more strict standards regarding their apps than android doe, so there's not malware, there's not viruses and things just work. If you already have an iPod and iPad, it doesn't make financial sense to get an android. You've spend your money in media and apps, why would you start over? I mean, that's our line of thinking now. We've had iPhones for more than four years. To go to a different platform now wouldn't make any sense.