I've had it on both of my N4s for a day now, and... it's fine. I'm not noticing any amazing improvements, nor any real issues, and I've re-rooted them both. I like the camera changes, but other than that, I honestly don't think I'd have noticed if it were changed (and re-rooted) without me knowing - it's just so similar to 4.2.2. Side-by-side might show obvious improvements, and battery life might improve, but it's not so major that you need to rush out and try to get it (unlike 4.2, which had some cool new stuff).
I have it on my old N7, and I like the features around app restrictions, as the kids and I both use that one. On the new N7, it's all I've ever known.
But... it's very nice, just lost in the overall awesomeness of the new N7.