Well even if it were an upgrade, don't you still have a 14-day return period to exchange it for a new phone if it doesn't work out for you?
Anyways, in my experience, the Galaxy Nexus has been an absolutely solid phone and now doubly so after flashing custom ROMs. But of course that's not for everyone. I seriously think data drops on LTE depends on your location. Lately it's been a lot better for me but it does occasionally happen at some places in the city where I live (Orlando, FL). Then again, that occurred even with my Bionic and Thunderbolt so I'm not going to lay the blame on my Gnex as the problem.
The screen has been great (no scratches so far), sound is okay if albeit comparatively fainter on stock Android ROMs, ICS is an amazing OS, I love the button placements, and the camera takes good photos. My only complaint is how easy it so to scratch the bottom edge of the phone when inserting a headphone jack or the micro USB cable.
I've switched through 3 phones last year (Droid X, Thunderbolt, and then the Bionic). Now that I have a Nexus, I think I can finally settle down on my phone binge. I'm planning to keep this phone for the duration of my contract. It's unfortunate that Verizon may never get another Nexus; for some reason I get the feeling the whole debacle with it's release here in the US left a sour taste in Google's mouth.