It all depends on the person. I know dudes who are ready to rock after 15 min; I don't start feelin' fast until ... well sometimes longer than an hour.
It also has to do with how much, and how you train.
That said, YES you are getting benefit from 1hr. Would you get MORE benefit from more... probably; but again it depends on if you did 6 hours the day before ya know. It also depends on how intense that hour is, I mean... if you start doing intervals after 15min of warmup... the first interval is going to hurt BAD because you wont be all that warm, but it will still do you some good.
Depending on what level you're trying to train at (ie, personal improvement v. win the rainbow), sometimes the best thing to be doing right now is just riding. Getting out (or in) as much as you can... an hour is better than nothing... and its definitely no small amount either. Don't short-change the intense-hour workout;they can really do wonders if done right.