I liked it. I really did. It felt like another old-school type of episode to me with the whole vengeful spirit vibe, of course the EMF meter, rock salt (in the form of salt rounds) and having people stay inside the salt circle. :)
Other things I enjoyed:
Sam's fear of clowns shown again. I loved his bitchface when he saw the photo of Chester dressed as a clown and immediately slid it over to Dean, lol. And then his reaction of seeing the clown in the elevator at the hospital, their stare-down complete with the elevator music in the background. And we finish that off with some badass!Sam making quick work of him! Though I do have a quibble: the guy wearing the costume (who was possessed by the spirit) was 60 years old?! Geez, he looks like he's at least 10 years older.
The cute one-liners when they were interrogating the rabbit dude. "What's up, Doc?", "wascally wabbit", and Sam's "let me guess, Rog - You were framed!" and then earning a look from Dean. Sam's "what?" was all "oh, so it's okay for you to make the cheesy references but not me?" LOL
I did think Donna and Doug were kinda cute at the end (and yeah, I liked how it was basically Sam who convinced her to give him a chance). She was pretty harsh & defensive toward him most of the time, though I understand why after dealing with her ex.
At first, Dean's beef with Sam praying to God bugged me a little, though I guess it makes sense. After all that's happened, Dean doesn't think they can count on God to help them fight the Darkness. He'd rather them fight it together. Which sounds great, brothers on the same side fighting something really big, but I do wonder if he's saying this - at least in part - due to what Amara said to him, about him not being able to fight/kill her. Maybe I'm overthinking it.
I see that Sam told Dean about his visions, about seeing the cage. He wonders if God is bringing him these visions, as if the secret to fighting off the Darkness is in there. Ooh, intriguing. Dean obviously does not want to go there, mentioning about what happened last time. As much as I'd love for Sam to save the day and see what's in there, I'm a bit uncomfortable with the idea of a total repeat of Swan Song...selfishly, I guess, because although I admired Sam for sacrificing himself to save the world ultimately, it still left me upset in the end (even though I knew he'd be back, lol). Sorry, I'll shut up now. ;)
Anyway I enjoyed this one. Loving the old school feel to a few of these episodes so far. :)