... worth it ...
I found my purchase of a trainer (just a basic old second hand one) the best purchase i'd made for a while. It *is* boring if you just sit there, there's no doubts about that but just do anything to take your mind off it and it's easier - i just stick on the box, or load up a movie...
Where is really comes into it's own is with bad weather/winter training and specific drills - at least i don't have to worry about other traffic/pedestrians/riders when doing one legged drills or standing accelerations etc and i can get out there at 6am for a pre-work session - when i can get my lazy backside out of my nice warm bed that is!
You may want to get a fan though as you'll not get any cooling effect like when you really ride!
Still, it sure ain't as much fun as really riding although i do hear that rollers are a bit more fun though!