GPS Design Review (RF Input)
It looks pretty reasonable to me. I've got a question and a comment. 

What are the components between the antenna and the GPS module? Any clocks etc? If they are power supply lines, it looks a little light on bypassing. 

I'd also drop a dozen or so ground vias under the antenna itself, placed randomly. The reasoning behind this is to make sure you don't create a resonant cavity under the antenna, with the walls formed by ground planes top and bottom, as well as the via holes running around the outside. Unlikely, as your pcb is likely to be lossy, but you'd hate to hit the jackpot with that.