Rated 3 out of 5 stars
It's not all that bad. Tweaktube has a lot of options and it's just a question of tweaking it so you can get past any problems like slow loading, lack of video, and unwanted video embedding. The styles are pretty, and does a good job with enhancing youtube. One problem is "registering" and doing a survey that could easily be done in other venues. That was annoying.
Beyond that, the plug in is actually quite good, but as mentioned in other reviews, it has some bugs that will slow down your Youtube experience.