We've been 3 times with our 3 (now) teens. The last time they did complain a bit that there wasn't much to do in the town itself. They said it was just 'walking up and down the boulevard' which is actually lovely but the shops are a bit same-y.
There's 3-4 decent beaches to choose from in the resort. Some activities break it up a bit - there's an OK waterpark in the middle of the resort, the Cesar Manrique house and the volcano tour were good. Surf lessons at Famara are great if the weather isn't too rough.