Okay, disclaimer here. I'm not a film critic, but I do tend to see things from a storytelling pov since I am a writer. So a lot of what I wrote is biased in that regard.
I have mixed feelings on it. I'm going to assume a lot of people didn't like the angel plot. Personally, the plot doesn't bother me. I'm not looking for a literal interpretation of the Bible or Christianity. For me, it's all fiction so nothing about that bothers me. And it looks like they are definitely going for some gray area which will keep the tension and conflict going. The "negative" view of the angels has been done before in previous tales. The grayer they keep this, the more room they have to work storywise.
I love Castiel more and more. Just saying.
My problem with the episode was actually on pacing again. The first half hour dragged. This was exposition to the extreme. SG-1 suffered from this a lot in its final days. The exposition in this episode just was very poorly executed which also made some of the dialog about grace stilted. Sam's research skills are good, but wow. Him figuring out the exact comet? That's a bit contrived. And I wasn't really feeling it between Anna and Dean, even if it was a "last time on Earth" moment. Once we got past the first half hour, the plot and sense of urgency kicked back in and then it was fine.
This was the opposite problem of last week. I felt their first half hour was awesome and then the show came to screeching halt for Sam's flashbacks. If TPTB had combined the first half hour from last week with the last half hour of this week, that would have been one fantastic episode. I still feel that Sam's flashbacks deserved their own episode. This isn't a slam on Sam or JP. Again, I had no problems with character or plot from last week. I just feel his meaty stuff would have been best in its own episode and that this two parter should have focused on the conflict between Heaven and Hell with the Winchesters stuck in the middle.
I also felt this two-parter suffered greatly from the budget problem. This needed to be an action packed two-partner, imo. I don't mean non-stop action. But the action element was really week. last weke you had Sam and Dean jump through a window. This week people stood around and talked alot. And the angels and demons stared at each other. Not quite so exciting. I'm going to say that their lack of money really affected on how "big" these eps could have been.
That said they weren't bad episodes. Their weaker episodes still are better than most stuff on TV. And the acting is top notch. Just like JP knocked it out of the park last week, JA had his turn to shine at the end of this episode. Both actors continue to excel and so do many of the guests.
End scene was killer. Poor Dean and Sam. But that is Hell and I expected no less. Neither episode makes me feel any less for the boys. Makes me wonder about John.
So in short I guess I can say great story, lousy execution. This probably looked better on paper than it did on screen. I enjoyed the content and many of the character moments - I'm still wondering if now both Dean and Sam sort of trusting Ruby is going to come back to bite them - but the pacing, sense of urgency, and overall execution hurt the story.
Onward into hiatus. Still, this season has been very good, but even the best shows have their weak moments. It was bound to happen. Hopefully, the rest of the season will remain strong. Still my fave show and I stand by it. It doesn't mean I can't call it on some of it's weaker moments :)