I think most of the complaints can be traced back to the animator trying to make Halo appeal to more mainstream anime viewers. Them having hair, for one thing, is meant to add some individuality/interest/artistic style. Super soldier chick with buzz cut = intimidating. Super soldier chick with long purple hair = hot/awesome (at least for the typical anime viewer; I don't watch much anime but I get the impression they like long oddly coloured hair). Most of the deviations from typical Halo stuff (like space bikes, Solomon not listening, etc.) seem like they're meant to turn Halo into a great sci-fi action-flick.
The armour seemed a bit strange, but I like it. It looked like MK IV armour, with a MK VI chest plate, and the helmet being a cross between MK V and MK VI; however it works and it's definitely recognisably Halo. Personally, I like their version of the EVA helmet much better. It's got a crease down the center that makes it look fast and sleek, not like the fish bowl Bungie's version is (no offense). The space bikes' weapons were a bit overpowered, but overall everything fit in the UNSC's design aesthetic. The prowler I didn't see enough of; the launch bay for the space bikes and the interior were all Halo, but the glimpse I saw of the prowler's overall form didn't match up. I liked it, but it just didn't seem UNSC.