Really pretty. Fun. Problems with control are typical of all 2 axis type controls. Trimming your thumbnails and using bursts (as opposed to trying to maintain a constant stream of fire - your thumb has a large contact area and thus precise control is difficult - so walking your fire into a moving target is difficult) might help. Could be a lot more precise, but its not supposed to be too easy, is it?
TL,DR - if you liked robotron 2048, 1.99 is a good price point. And theres no IAP crap, which is a pleasant surprise from Activision.
Addendum: playing on an iPad Air 2, only on level 4.
Update: on iPad pro, gameplay is much improved. Controls are more responsive, graphics much crisper.
3.14159... about Geometry Wars 3: Dimensions Evolved