Well to be fair, the rank system was very realistic, when you met a true level 40 or up, you know you were getting tossed around a few times. In Halo 3, it seemed like there was a large skill gap still after reachin lv 50. I could play level 50s and win without much trouble, and other times I would have no chance. If you never had the chance to experience H2 rank system you would agree.
The clan tab is just a great idea with no real negatives, its like an extra friends list that is 100x more convinient then "friends of friends".
And the map quality is a thing of preference, but I think most people agree, H2 didnt really have any bad maps, and I cant think of any I disliked in Halo 3. The only beef I got with Reach maps is they are all on forge world and are not very original.