So... what can I do with my Droid 3 that I couldn't do with my Droid 1?
Anything goes...
I had my Droid 1 for just over a year and a half. It was my first Android experience and I absolutely loved it. I was terrified of upgrading. I don't need a media-specific phone and I certainly wasn't looking for a ton of features that I'd never use. I wanted what i had, only better. Suffice it to say that after some research, I'm supremely happy with my (now 1 week old) Droid 3. It's exactly what I wanted. I have no experience with the previous model, so I couldn't say how they compare, but I can tell you that after a minor one day learning curve this phone has made me uniquely happy.
The Dual Core processor stripped away my Internet Browsing and Gaming woes. It's
blazing fast and I've not seen a glimpse of lag once. The extra screen realestate (and HD display), believe it or not, makes a significant difference in viewing. The new UI is so slick I haven't even bothered to download my paid ADWEx app... though at some point I may get tired of blue (we'll see). After that, at least half of the new preloaded apps are super useful... some of my most used now are Quick-Office, MotoPrint, and the new File-browser and Task manager.
One of the most useful things I've come to find is the DLNA access. Basically gives me access to any server (or my PC, in my case) nearby and stream or download to and fro. Awesome for pics, movies, & videos. This feature is a preloaded app, but it's also integrated into critical areas such as the new Photo gallery. I swapped my SD over from my D1, so my gallery is a bit of a mess, but there's now options to create albums---which is pretty cool even if I haven't gotten to doing it yet. Likewise, I haven't toyed with the HDMI ports yet, so i'm not sure how well it translates to screen. But like I said, I wasn't looking for a media-oriented phone. I look at this option like a cool bonus.
I happened to like that the D1 had some weight to it, and the D3 does as well. The physical Keyboard is certainly improved, and much easier to type on (the buttons feel more like buttons). The notification light was an important thing for me to keep, because I rely on it pretty heavily at the office. It remains (thank heavens!) with the addition of the front-facing cam just next to it. As for taking pictures, lots of new options including some standard filters and a improved UI and reaction time at button-press.
My only real gripe is barely one... there's not a super cool clock widget, but hey, that's what the app market it for!
Overall, if you really like your D1, you will absolutely adore your D3.