Should I use 2' x 2' tiles for a galley kitchen?
You really need to have a solid surface for large tiles.  The actual tiling is not the hard part.  You need to make sure you have a very very flat concrete or backer board subfloor.  

As for installing the tiles the only thing "harder" is that you will have to back butter your tiles.  Also if you mess up a cut bad it costs you more.  

The flip side is if your subfloor is set up right you can have a really nice looking kitchen floor.  The big tiles do look nicer and clean easier.  Also if you start in the right spot all/most of your cut edges can be hidden easier.