I bought the Captivate a few weeks ago, and I took it back for the IP4 after exhaustive use/thought and review reading. I have to say that they are both good options (best 2 ATT phones), and I can't say the Droid is bad or inferior at all.
In the end, the Retina display is easier on these 40 year old eyes. While the Captivates super AMOLED screen with 1/2" more real estate is much more exciting to look at, the amazing contrast actually makes it hard to look at for too long. Wow vs practical. iOS is still better but Droid is coming up fast.
Overall, Apple's refinement and polish physically and digitally is still untouched. I'm good for 2 years.