I've had the Droid Ultra for about a week now, upgraded from a Galaxy Nexus. David's review of the phone really was inaccurate and wrong. I understand that it has no reason to exist, but that shouldn't warrant a bad score. I still bought it, and many others will too. So here's a short review based on my experience with the device so far.
Smoothest Android phone I've used, better than the Nexus 4. I haven't noticed any lag whatsoever, even when switching between very demanding applications. Unlike my Galaxy Nexus, the keyboard pops-up instantly and there's no delay between pressing the keys and displaying the text typed.
Honestly, I don't think it's as bad as some reviews claim. The top bezel is very small compared to other phones, and the "chin" provides a little extra durability in case of drops. The back does gather fingerprints, but you're never actually going to be looking at the back of the phone regularly. If you're that upset about it, you can just grab a case for $10. The phone is actually easier to use with one hand than my Nexus was, mostly due to the square bottom. It's definitely not as good as the Moto X's hardware, but not as bad as David claimed.
Coming from a Galaxy Nexus, the battery life on the Ultra is phenomenal. I can easily get a full day of moderate use in with percentage to spare. I'd usually come home from school with 20% on the Nexus. Now I'm arriving with 60%. With the screen at 100% brightness, it only uses 35% battery, compared with the 30% that "Android OS" uses.
The screen is decent. It's much brighter than my old Nexus, and isn't as prone to burn-in. However, it has a red-ish tint that is especially evident on low brightness settings. I suppose it's better than the blue-ish tint that most AMOLED screens show.
It's definitely an upgrade from my old phone, but nowhere near as good as other flagships. It takes good dark photos and opens very quickly, but other than that, it's bad. 1/10 photos will either be very out of focus, blurry, or have lines through it where it looks like it's trying to adjust brightness. The flick-to-use camera function is almost flawless though, and I used it much more than I thought I would.
When it works, it's great. But occasionally it will miss the "Okay Google Now" command altogether, and I find myself repeating it multiple times. Once it catches the trigger words, it works flawlessly. It hasn't ever misinterpreted my commands and is much more functional than I thought it would be. I could be in another room and yell "OK Google Now, play Radioactive" and it will open Spotify and play the song. Before then I didn't even realize Google Now worked with third party apps.
Easily the best feature of the phone. While school is in session, I can pull the phone out of my pocket and it will display the time without me pressing the power button or tapping the screen. I can also set it on my nightstand and just bump the phone to check the time. It knows when it's face down on a desk, in a pocket or purse, or in the car, and adjusts to the circumstances.