Regarding lag, it exists but it's far from intolerable imo. Things are usually _very_ fluid but if you have enough things syncing in the background at a time the animations may lose their usual buttery smoothness. Basically the phone isn't completely lag-free so if you're coming in from a top-of-the-line high-spec previous phone this might be an issue for you. If you're coming from something like the N900 or some other dated and/or midrange phone though, you'll feel like you're flying

About freezing I've already encountered it twice but under what I consider reasonable circumstances: once right after I installed and ran an app from my ISP, and another once when I was messing around with apps and developer mode stuff. I like picking my things apart, but "normal" operations, in my experience so far, have been perfectly fine and flawless.