I loved this episode (but then again I love every Castle episode...) it was great to see the conflict of opinions between Castle and Beckett when we're so used to seeing a compromise or acceptance of each others differences (eg; fate, psychics, etc...) but then again it's not much fun to see Castle and Beckett argue but that shows us that not everything is as perfect as it seems between them (with of course the exception of them being together)
I really didn't see the ending coming, I always expected that Castle's friend had killed his wife and was shocked when it was actually Amber, I was cursing my detective skills until I found out the guy (whose name escapes me) wasn't really all that innocent!
I REALLY have to mention this sorry!
did anyone pick up on Esposito and Beckett's conversation about Valentine's Day at the start when he asked if she'd be spending it with Josh and she said that they were a cop and surgeon and didn't have a couple of hours to spend? And THEN at the end Castle was upset and Beckett offered to buy him a drink and when he mentioned her spending Valentine's with Josh she said she had a couple of hours to kill :D
*sigh* I love this show