Nothing gets cut in half when running Windows via Bootcamp - it's just a piece of SW to help your Macbook manage its Windows related stuff (drivers, bootloader, drive partitioning etc) and then help it fire up Windows just like you would on any laptop - natively and without any virtualization of any kind. Basically it turns a MB into a shiny beautiful full-blown Windows machine.
While gaming on a Mac nowadays is getting straightforward and easy thanks to services like Steam or gaming natively via Bootcamp, gaming on a [super thin and portable aluminium] Macbook is still far from ideal. The Iris and Iris Pro GPUs are surprisingly capable and running Half Life 2 or Portal or CoD4:MW or Minecraft or (insert your favorite classic) in half of the retina resolution (1440x900) is a piece of cake for both of them (and obviously for the top dGPU model), things can get pretty hot when trying to run demanding games or even older titles without a FPS lock. 40 FPS locked Half Life 2 is smooth as butter and a pleasure to go run/drive/shoot through, and 60 FPS locked and Vsynced Minecraft is as much fun as you can imagine, burning through HL2 at 130 FPS or Minecraft at 190 FPS with temperatures going through the roof, your hands on fire and fans spinning at a million RPM is a pain. It's not a gaming machine. With a proper FPS lock (easier in Windows), running proper less demanding games - great, enjoy hours of fun. For everything else, use a cheaper Windows gaming rig or a console.
And don't worry about switching to OS X - it works just as you would expect and it's very easy to pick up on the fly. Bring your Macbook home and enjoy it from day one (you will) and there's nothing that could go wrong.