Uncharacteristically, I bought the Google Nexus One phone without actually seeing it or waiting to see what problems other people have first. (This is mostly due to my wireless contract coming up and my desire to switch to T-Mobile anyway, where I save a lot of money using the family plan.) So this is my review after having it for a bit less than a day.
I already had an iPod Touch, so that is my main point of comparison.
So far, I think that the iPod has a better interface. Android isn't bad, but I miss multi-touch and sometimes the phone doesn't seem to register that I am touching the screen. The onscreen keyboard is almost as good as Apple's, but I don't seem to be able to type as quickly with it. Google has a much better system for guessing words, though.
I am indeed having the problems that others are complaining about with very spotty 3G coverage and the phone almost always goes to the very slow Edge network instead. I am assuming that Google and T-Mobile will get this squared away. (Junior Elder, who just got an older Android phone, is laughing at me as his is zipping along fine.)
The voice recognition is pretty nifty, but it requires a consistent Internet connection to work.
As I just discovered, I get zero coverage in the restroom at work, which is very frustrating (that is some of my best surfing time.)
Android Market is pretty good, but not nearly as complete as the Apple Store. for example, I couldn't find any free office automation apps.
The screen is gorgeous, but it attracts fingerprints.
Integration with Google applications (although not Google Apps) is pretty seamless. Google Talk, mail, contact lists and calendar work fine. It will automatically take the pictures from your Google contact list, which is cute. I was able to connect to other email sources, like an Exchange server, after a little playing. Yahoo Mail, for some reason, is not supported, but I downloaded a decent Yahoo browser app that makes it work well online. (I imagine Yahoo Mail Plus will work with POP.)
The battery seems to go low pretty quickly; I probably need to turn off some of the services to extend it. You need to be careful - if you keep Twitter on all the time, for example, that can suck out your battery quickly.
I am not a fan of iTunes, but I didn't like the interface to connect the internal MicroSD card to the computer. You have to "mount" the drive first, which seems silly, and I had problems accessing the files while it was plugged in to USB.
It uses a micro-USB cable, which is a bit of a pain.
The media player is competent but nothing spectacular. It can't play AVI files, for example (neither can the iPod, but I was hoping for better.) On the iPod I can change the size of the video display, but couldn't on the Nexus.
I love the form factor - it is only a little thicker than the iPod Touch and thinner than the iPhone. Don't have a good clip-on case for it, yet.
I still haven't gotten the GPS to pinpoint where I am, let alone get the supposed voice directions to work.
Still looking for a Siddur and the other Jewish texts I had on the iPod.
In short, it is not a bad phone, but not worth the amount I paid for it. Should have waited for the Nexus Two.