My 2c..
To me, my DNA feels faster now and I didn't think that was possible because it was already lightning to begin with. My battery life seems to have improved, which was a nice surprise. I didn't think I would like the new calendar but I am a fan of that now too. Although, I think I still like google calendar better. I am still getting used to blinkfeed. I have enjoyed it so far, I just dont know if it's enough for me to want to keep it on. Before that I was just using play newsstand which I still like better. I think the stock messaging app is worlds better. It had some lag for me before (bringing up keyboard and taking a couple secs to send the message after I hit the send button) and its still there which is a bummer, but as far as I can tell it seems to be the only place anything lags. Overall UI design I think is fantastic. I love most of the new app icons and widgets.
TL;DR
IMO the phone runs smoother and looks better with new features I enjoy. For the most part I am a happy camper
I will probably keep sense 5 as my default launcher for a while now and keep nova on the back burner.