My 550 came with:
combination 10/12mm open end
combination 14/17mm open end
24 (I think, could be 27) mm closed wrench for removing the rear axle
screwdriver handle with changeable ends (Phillips and reg)
Pliers
spark plug wrench
a little shaft with two prongs on the end of it, I'm not sure what it's for, maybe prying something out.
I think I'm missing a few tools as well. As for if I use it, yes! All the time. You'd be amazed at how much you can do with just the two combination wrenches, and a screwdriver. The pliers are useless though. If you're looking for suggestions of what to carry around in there, a metric wrench kit, some pliers, and a couple screwdrivers should get you about everywhere you need to go.