I would not do more than 3 lines. That is largely a matter of taste though. For instance :
Super spinner from Michel Bujardet : go round the world and keep stress away with this pocket size, led powered, ball bearing wonder.
The title is the first thing a prospect sees. It's got to make a difference. But indeed, it is part of a whole. The best title on a crummy page with one picture and an indigent description won't make much difference.