@tendoboy
I haven't had any performance issues with my Kindle Fire. I agree with you about the locked down Android OS. The interface can have a slightly less than snappy feel sometimes, but never bad. But the UI is actually pretty solid once you get used to it. Also it's easy to change the default UI (GoLauncher) and customize it however you want without any hacks/rooting it. While the Amazon Appstore isn't great, you can still find pretty much anything you could want. My experience is when there is so many apps ( hundreds of thousands ) it's a pain in the ass to filter through them. Also, it means there are most likely thousands of garbage apps as well.
As an example I've got a few good gameloft games running perfect Modern Combat 3, etc. I've got snes and genesis emulators that run perfect . I can stream Netflix, listen to the radio, watch youtube videos, surf the net, listen to music. I've even got it setup as a wireless midi controller. I mean it does anything you could want it to do. And remember before the Nexus it was the only budget tablet (got mine for $170).
The Nexus is appealing, and better in alot of ways than the Fire. But I don't think it's that much better honestly. In fact imho they missed one of the biggest selling points over the Fire, storage! They should have included a micro sd card slot.
That's my experience in a nutshell.