No complaints with regards to the anime as a whole.
The story, characters , and fights are all interesting and well executed. The animation is stunning, some of the best ive seen. Whether you prefer dub or sub you wont be disappointed by the voice acting. The only thing negative i have to say about the series is that the first episode is a giant info dump (could have maybe spread some of the exposition out a bit more) and that with such a large cast i felt some didn't get their due in terms of screen time.
As for the collectors edition itself, you get a nice thick cardboard box. Inside is the standard collection one dvd and a place holder box (to keep part one from moving about until you get part 2). The art work is very nice and the box solid but doesn't come with anything else to differentiate itself from the standard edition. So essentially it looks nicer, and nothing else. I didn't pay much more for the collectors than the standard at the time, but if the price gap increases you have to decide how much aesthetics appeal really means to you.