Overall I've enjoyed the Spirit S-315 and am glad I purchased a Weber. I've followed their grilling recommendations for everything we've put on the grill, and it has come out great every time. We use it multiple times a week. It heats up quickly and evenly. 

On the negative side, I feel that the door to the bottom of the grill is flimsy. Also, if I didn't store the grill inside and clean the cookbox and grease tray very regularly, I would find it hard to believe that those parts would hold up for 10 years. They aren't as heavy duty as I expected. Depending on your circumstances, it may be worth upgrading to the Genesis model.