It's a game that's definitely heavier on storyline and exploration than it is on combat, so I really enjoyed them for that reasons. I'm a history nerd so I loved it being set in ancient Rome, Constantinople, Egypt, 18th cent. Caribbean.

Good amount of puzzles/problem solving in Egyptian pyramids or giant tombs under Rome.

There's a bunch of volumes of the game, so it really depends on which one(s) you play.

I'd argue it's a bit of a button masher, but it depends on difficulty level & which edition you're playing. Later games have better combat.

There's a common storyline but it's not critical to keep up with. You can start with any game.

In a lot of the games there's this meta storyline where your character is in the present, but he's able to inhabit the body of his ancestors. These meta breaks got tedious after a while but they never take up too much time.

My favorites are:

AC II
AC II Brotherhood
AC II Revelations
AC IV Black Flag (pirating & sailing)
AC Origins (Ancient Egypt)

Admittedly I haven't played some of the recent ones:

AC Rogue
AC Unity
AC Syndicate
AC Odyssey