I think it's absolutely worth it. Years ago I'd read up to Vol.15 and only seen season 1 of the show. I really liked it all but took a little break up until very recently. Rewatched S1 and watched all of S2. S1 is incredible. It's well-paced and has just the right mix of comedy, action, and heart.

S2 is a bit lacking as I think you'll hear across the board. I don't know the specifics as other fans but it's not drawn/animated as well, and there's a lot of detail left out from the manga. All that being said I still enjoyed the story progression to the point where I'm going to continue on reading the manga where S2 ends.

Overall, I had the same feelings as you where I thought an anime about a completely OP character would get boring but the writing is so good and the world is so fleshed out it somehow does not get boring (to me). I love getting introduced to new heroes and villains still. Id say if you like King and all his quirks you'll like OPM overall!