I have stock 4.1.1 installed.
The good:
Very stable OS.
The phone is pretty speedy and doesn't lag very often.
The screen looks great (especially if at full brightness, where it belongs...).
When on WiFi, I can get over 3 hours of screen time on a single charge (I *think* that is good).
The bad:
The radios suck.
When you are not on WiFi, the battery life sucks also as a result.
Did I mention the radios suck? I am in the heart of 4G territory but am lucky to get a 4G signal at home. At my office (in a major metropolitan area) I set 10 feet from the windows and am lucky to get a 3G signal.
Did I mention how bad the battery life sucks when not on WiFi? It really, really sucks when I am at my office. When this phone cannot get a super strong, super solid data signal, it burns through battery power faster than Obama burns through the federal deficit.
It depends:
The camera for me is actually pretty good and I get compliments on my photos all the time (including indoor photos). It far surpasses the iPhone 4 camera but I don't know about newer iPhone models or One X, S3, etc.