yea it is, its in like a toothpaste tube, its blue and real sticky, ive never had mine leak with it on (goes and touches wood).
if you wanted to, wou could buy some gasket paper and make a gasket but theres no point really.
only other thing is you will loose quite a bit of water, leave the radiator cap on and that sould limit it tho.
get a good fitting hexagon socket and work the 3 10mm bolts loose, pull the end off, (i leave the pipe on it mainly so i dont loose it lol) flick the stat out with a screw driver as it will probably be stuck in, clean the faces up, wipe it down put the new stat in the right way up (its marked on it) put the new gasket/blue hylomar or both on, and then put it back together.
fire her up let it warm up, keep checking for leaks. if there arent any, take her for a spin.
like i said earlier, if youve got the tools to hand and you know what your doing it should only take to 20mins, but that can depend on how the bolts come out of the stat housing, sometimes they can be a bit of a pain.