If you love Bioshock 2, you'll likely enjoy it. Or should I say, if you enjoyed the "protecting the little sisters" aspect of B2 then you'll enjoy it. Each level is set up in a way that you only have access to certain weapons and tonics. It's a great way to fiddle with weapons & powers that you didn't play with in the main game.
It only takes a few hours to complete.
IIRC, there is a tonic you only get from Protector Trials that is good for Minerva's Den.