Indeed, a great bike.
I suggest reading up a bit on bicycle basic maintenance, and going over the whole bike. make sure the wheels are straight (spin then, and check the metal rim next to the brake pads, they should have no up/down, and no more than a millimeter or so of side to side). plink all the spokes of both wheels, and make sure none are excessively loose or tight. the wheel and crank bearings shouldn't have any side to side rattle, ditto the headset (steering) should have zero play, but be smooth and friction free. inspect the cables, there should be no rust on any exposed stretches of cables, if they are corroded plan on replacing them (cables are cheap).
take a test ride on a smooth quiet street, and go through all the gears (except 1-8 and 3-1, you never use these 'crossover' gears) one at a time, they should shift crisply and be quiet. actually, gears 1-6 and 3-7 aren't real important (eg, I only use the 'granny gear' small chainring in front with the bigger 4-5 gears in back, these gears are strictly for climbing steep hills when 2-1 isn't low enough.)
make sure the brakes levers can't be squeezed all the way to the bars, and that the pads don't scrape on the rims when you spin the wheels with the brakes released (easy to readjust). when you stop, the brakes should be smooth and not shudder or squeal. if they do, clean any rubber residue off the rims, and the brakes might need their pads re-aligned.
websites like Sheldon Brown's site, and the howto's on park tools site explain how to do nearly everything you might need to tweak.
http://www.parktool.com/blog/repair-help
http://www.sheldonbrown.com/articles.html