I made the switch 2 weeks ago, my iPhone 4 still in my drawer just in case. Still missing Words with Friends and Plants vs Zombies(actually going over withdraw syndrome...)
Had to do some work to get the Droid X to be as usable as the iPhone, for example, goodbye Verizon crap and hello Froyo vanilla!! Then finding the right apps, free and paid ones, spent about 20 bucks to make things the way I wanted.
Don't expect a better phone without putting some blood, sweat and tears on it.. But the reward is great when it becomes YOUR phone.
Start with getting rid of the original ROM, battery life is amazing if you pick the correct ROM(I got Fission), I went from 4-5 hrs from full to dead to at least 10 hours of full usage, actually better the the iPhone 4