Great place if you like peace & quiet.
Everything closed by 11ish, NOT a party island.
The walking is superb, but can be properly exposed.
The gorge walk up to Monte is great, combined with the Levada dos Tournos over to the Hortensia Tea Rooms it makes a cracking day out.
People are friendly, the food is cheap and plentiful and taxis are good
value.
The local specialities are battered fish and lamb kebabs!
Didn’t see any mtb routes when we were there, but it looks superb for riding.
Basically a big volcano so very steep.
I’d go again.
That basically sums up my experience of the island, too. I’d certainly love to go again.
Edit:
Should add there aren’t any beaches on the main island, which may or may not be a disadvantage.