Its the same advice I gave before on the droid v. iphone thread. It comes down to preference to be perfectly honest. I have a droid x, and it works ok over all, but the longer i'm with it the klunkier I find the OS to be. iOS is simple, effective, and very user friendly. Droid is a little more like an actual Linux system where you can pull back the hood and futz with things to make it better, but if you aren't that tech savvy, it might not be the choice for you.
Google offers free services for things Apple charges you for (google calendar/contacts etc sync, vs. mobile me subscription).
The apps are a wash. By now, just about every app on the iPhone is available for the Droid. And unlike the iPhone, there are apps for droid that you can modify the way the phone works and it doesn't require you to jailbreak the phone since Droid allows for beta testing apps from outside its market. There are also easy/free apps for tethering for droid that don't require any payment what so ever (but if you want to be clued into that, send me a message because I'm not going to advertise for that program). App store will always have more focus on it, and will always get new apps first.
If you have a touch screen phone already, the change to the iPhone won't be a big leap. Same with the droid, but if you want to take a baby step into touch screen technology from your current phone, droid 2 having a keyboard is a nice feature.
Again, this is most of the same stuff I covered in the other post, and the Droid 2 has been around for a pretty decent while, as well as the iPhone 4. So since these responses haven't changed, I'd suggest that if you can hold out, I'd wait until the middle of summer or fall and wait for the iPhone 5/4s (whatever Apple will call it) or a new Android based device and see if something comes along to blow your mind. You're currently on the cusp of the summer technology release season before the end of the school year which carries retailers until the fall when releases and spending really picks up again. So you're about to get a handful of new choices. Let the early adopters crash and burn on the devices and read their reviews before you make your choice.