Depends on what all you need. I have no bad data reception or anything and don't use wifi ever as 4G does just fine for me. My home isp is only a little bit faster and I don't see much battery difference so no need to switch. I haven't had the MAXX so I'm not sure if reception is any better.
The MAXX and RAZR are both just too wide for me in the hand(and the original RAZR feels way too thin) and just feel awkward, but the extra bulk does help a little on the MAXX. I'm honestly just not a RAZR fan however, if it wasn't for the Nexus I'd have the Rezound or would have stuck with the Droid 3 until a better phone came out. Upgrading to the RAZR wouldn't have felt like an upgrade besides having 4G considering the Droid 3 OS is about exactly the same.'
The only con I have with the Nexus is that it IS a bit too slippery lol, and I'm not a fan of the grainy screen when the brightness is down even though I'm used to it now and don't really notice it. I usually have it up all the way though when I'm at home though so no problems.
I'm not a casual phone user so.. having the dev support is a MUST. RAZR and other Moto phones have dev support obviously, just not like the Nexus.
And no you won't be getting official ICS any time "soon" with Moto's release for estimated dates. You'll likely be getting that when Android 5.0 is rumored to be out already.. and if I stick with the Nexus instead of upgrading to a phone that has that, we should get the ported to the Nexus fairly easy. So that's another win.