I started it for Nathan Fillion too and I agree... It was a boring procedural and I ended up keep watching just for Nathan and Stana (Castle and Becket) they were amazing, but yes I can't remember anything that's not related to them or his family... Never really connected with the other characters and I believe I actually skipped a couple of seasons watching just the clips about the couple... It went on for too long... but procedurals tend to air for a very long time...