I've had my Droid for about two weeks now, so here is my impression comparred to the iPhone I had.
First, the battery life of the new Droid is less than a new iPhone. I need to charge it every other day, whereas the iPhone could go four or five days without a charge.
Second, navigating the Droid isn't as instinctive as the iPhone. It's easy to navigate the iPhone. It has better shortcuts and it's easier to make a call from the Favorites list.
Third, the droid forces you to delete the entire text thread. The iPhone lets you delete individual entries and it keeps the name active.
Fourth, I liked downloading the Apps into iTunes and then onto the phone. The Droid forces you to download them directly with the phone which can eat up battery life.
Fifth, I liked having a seperate headphone and charging jack with the iPhone. The Droid only has one jack so you can't charge and talk handsfree at the same time if you use headphones.
Sixth, if you want to lock the phone the mechanism to unlock is goofy. Instead of entering in a number combination like the iPhone, you have to drag your finger over the screen and connect the dots. It's awkward to do while driving.
Seventh, enlarging the screen isn't as easy as the iPhone. Tap twice and it's bigger with the iPhone. With the droid you have to use the magnifier. PITA.
Now for the good stuff. The Droid has as many good Apps as Apple, and some are better. There are "widgets" that you can put on your screen that give you live, up to the minute, updates. Pretty cool if you are out doing errands and want to keep an eye on NFL and NHL scores. The Google Map App is awesome with the free built in GPS. The best part of the Droid is the price of the phone and my service plan. I paid $98 at Walmart and my monthly service for unlimited everything is $82.00 including all bull$hit fees and taxes with T-Mobile.
So there it is. If you had an iPhone, the Droid is almost as good. If you never had an iPhone, then you don't know any better. I myself liked the iPhone better but I didn't want to spend $600 for an unlocked 3GS this time around.