Just got the Droid 3, switching from a Droid Charge I used for about a month. Droid Charge wasn't a bad phone, mine just had a particular defect and rather than get another Charge, I opted for a Droid 3. Main reason being that I used the 4g way less than I thought I would, therefore a quicker dual core phone was more of a priority than 4g.
First Impression (Compared to Droid Charge)
Screen: Well obviously this is no comparison, as soon as I gave up my Charge and turned on this phone, I can only describe the look as old and faded. Though I don't think the Droid 3 has a bad screen on it's own, just unfair in comparison to the Charge in particular.
Overall Speed: This phone really shines in this department, the speed was immediately noticeable upon switching. Was very relieving and refreshing to be using this phone. I personally thought the Charge was very sluggish and laggy. I tried launcher pro and go launcher on my Charge, and while it did improve the feel, it still suffered from major home screen redraw when I came out of apps/browser. I haven't noticed much of that on this Droid 3.
Camera: Not to be harsh but the camera really sucks on this phone. Hard to imagine they would let it release like this if they tested it at all. Like others have mentioned, the blue tint, and it's pretty slow to actually take a picture compared to other phones. I haven't tested quality/sharpness of the photo yet, I assume that would be on par with others though. Like others have mentioned, during video recording, it struggled to focus. The Charge also uses auto focus but it's definitely nowhere near this bad. When playing video back on the comp, I notice an odd ripple effect blur to the whole screen, subtle but noticeable. somewhat looks like it would if you filtered an ocean ripple effect through photo shop.
GPS: I use the navigation a lot, and I had assumed that all phones were equal in this department, but I was definitely wrong. I first had the Droid Incredible, and navigation was great on that, instantly picking up the signal. Then came the Droid Charge...wow this thing really struggled with picking up the signal. It doesn't take too long to actually grab text directions, but there was many a time it took about 3-5 minutes while driving for the voice to finally start sending out turn by turn directions. So far, the Droid 3 pops navi starts instantly, will have to use it a bit more but really nice so far.
MISC: Don't really have much to say about the UI, since a lot of people switch launchers and what not. But stock for stock, Droid 3 would definitely get the edge, I've never experienced a worse launcher than the touchwiz on the Charge.
I can't really comment on the keyboard since this is my first phone with a physical keyboard.
As far as 4g is concerned, yes it was definitely fast, but not without its problems. I have full signal/4g coverage at my house, and many a time the 4g would stop, suddenly switch to 1x, then 3g, then back to 4g. Wasn't a big deal to me since I used Wifi all the time, but for those of you who were thinking about using 4g for the majority of the time, it could become nuisance.
I've only used it for half a day but overall I am pleased with this phone. Like I said, I didn't hate the Charge, but I think given the option again, based on my needs, I would prefer the Droid 3.