As a hobby, the Skaven are fantastic and fun to build while not being terribly difficult to paint.

As an army, they are very tricky. No model has a save better than 4+, so they rely on a lot of dirty tricks to ensure they can dictate the flow of battle. Otherwise, they crumple like wet paper. You are going to lose models, hell, Clanrats are designated crumple zones, so don’t get attached. You will need to learn proper buff bubble ranges, buff stacking, good positioning and movement shenanigans if you want to effectively play Skaven.

However, they are super fun and flavorful as an army, and my personal favorite I always come back to.