I always carry both, and extra batteries. You can't beat GPS for scouting, marking trails and stand locations, etc. Its also great to just be able to hit goto and get back to your truck. I'm not into orienteering, and the compass can generally get me back to the road I came from, but the GPS has saved me some steps on more than one occasion. Also, you can't take your compass home, plug it into your computer, and mark a topo with your favorite locations, show the tracklog for where you've been, call up an arial photo or topo map of new areas that you just scouted for the first time...

Also, I've looked up new areas on the computer, picked out interesting spots on a map and noted their GPS coordinates. Take those coordinates and plug them into your GPS (or just download them) and you can get to a spot you've never been to before. I even use the GPS to mark where I should start looking for somewhere to park the truck when hunting a new area. With free software such as EasyGPS or USAphotomaps the GPS is a very powerful tool. Its great to have the ability to mark your stand locations on a map, print it out, take it to the woods with you or give to your wife so she knows where to tell the authorities to start looking if you never make it back (assuming if you want to be found).