I mostly did. The sights and museums in Athens were nice, but the city itself is honestly pretty dusty and chaotic, and also surprisingly expensive. I want to return though, I've got Meteora on my bucket list, and I also hear Thessaloniki is quite nice.
I pretty much flew in on a whim without any sort of plan whatsoever, which on one hand felt freeing and exciting, as I haven't done this before (alone no less), but on the other I was clueless and probably spent more time thinking about what to visit and see than actually visiting and seeing stuff, and probably missed lot of interesting places.