I suspect people with the lag issues are the ones who were too lazy to do a clean flash! I've not had any issues at all. There was initially a bit of lag, but I guess that's what you get when you're installing over 50 APKs one after the other! Nearly a day now, and I'm pretty pleased with the speed and responsiveness. Of course, I didn't stay with the stock kernel for long. The colors sucked too much!
You're right about the "toggles" being a disappointment! The layout is pretty neat, but the fact that they're actually more shortcuts than toggles is a big letdown. Also, there's no GPS "toggle"!
The lockscreen widgets haven't left me very impressed. Looks like some half-baked attempt at lockscreen widgets. Could've been done on purpose so there's some "new features" for the next Android update, or maybe just a rushed job! Either way, they might as well have not put it in there. I guess it's back to Widget Locker for me!
I'm not really seeing any lag on the recent apps list or when the screen is switched off. And the camera thing is that when the orientation is changed from portrait to landscape or vice versa, the buttons also rotate, which is really not necessary because they end up in the same place anyway! Not a big deal for me, since auto-rotation is something I usually leave off! In fact, it shouldn't be a big deal at all!
Wifi and the phone signal seems to have improved quite a bit over 4.1.2, that's for sure. I get much better range in the same place than I did when I was on 4.1.2, so I'd upgrade for that alone! And I'm sure that once the custom ROMs start coming out, things will only improve from here on.