Aiming is fine, and like I said, vehicle control makes it easier, but the Hammerhead is to weak. But, where there is a positive, a negative presents itself. There are beautiful vistas, big ponds, waterfalls, its all good to luck at. The exploration is good, because of the easy navigation and how nice the enviroment around you is.
There are even some platforming parts with the Hammerhead, which are actually quite enjoyable. They are split up by normal gameplay on foot. Shepard and squad drop down onto a uncharted world, much like the Mako from Mass Effect 1. Overlord brings back the Hammerhead, the vehicle from the earlier Firewalker DLC. Mass Effect 2, arguably one of the biggest games of 2010 so far, has had new DLC come out last week, Overlord.
