My first Android phone was HTC's Desire HD a year ago, and the Galaxy Nexus looked like a great opportunity to upgrade - being the first new Android with a major software upgrade and nearly all-round improved specs.
The the first thing I noticed was how insanely light it is compared to my Desire HD, despite having a larger screen. Partly this is due to the plastic build, and although I'll miss the DHD's aluminium frame, the trade-off is definitely worthwhile, and the Galaxy Nexus still feels well built.
It was great to see all my Apps automatically download when I first turned on the phone. A couple are missing as they haven't been updated for Android 4.0, and my beloved Swype keyboard also won't work yet*, but I expect these will be fixed soon enough.
The most promoted new features in Android 4.0 haven't blown me away. Face unlock is fun to try, but I'm not convinced it's any quicker or safer than pattern unlock. Android Beam will only work with other Galaxy Nexus's currently - bit pointless when I don't know anyone else with one.
The new on-screen buttons work well, and the choice to remove Menu and Search makes things a lot simpler. Apps like YouTube can hide the buttons giving extra screen space, which is a genius idea - just too bad not many apps take advantage of it (yet).
Where Android 4.0 really shines though is the vast amount of small improvements. A lot of these, such as customizable dock items, Chrome bookmark sync and improved folders and contacts were things I'd added to Android 2.3 with third party apps, but that often resulted in a mess of styles and UI's. Having them all built in the system makes the OS far nicer to use, and it was satisfying to uninstall about half my apps just for not being needed any more. For average users who don't bother too much with customizations, it's a massive step forwards.
The screen is the first in the UK with 720p, and along with Samsung's super bright display it looks incredible. I'd say the resolution increase from QHD is only slightly noticeable, maybe something to do with the pentile matrix, but this is still the best screen I've seen on any current smartphone.
Some people have complained about the camera only being 5mpx, but I find photos more clear than the 8mpx shooter on my Desire HD. My only possible gripe is that zooming can look a bit grainy, not something I noticed before.
After a few days of use it's hard to judge the battery life, but it seems to get through a day with most of it's charge left. I still wouldn't risk going away for a night without my charger, but it seems pretty good considering the display size.
If you're thinking of switching to a Galaxy Nexus it might be worth waiting to see what Android 4.0 flagships Samsung and HTC come out with next year, not only for hardware improvements but also to give certain apps to catch up with Android 4.0 and make full use of it's potential.
If you are buying a new Android handset now though, I'd say don't even consider any phone still shipping with 2.3 - Android 4.0 is lightyears ahead.
----------
*It's February, and Swype for Android 4.0 is here! First impressions are that it works as well as before, I think it's massive improvement on the stock keyboard.
