The previews said that a "beloved character" faced death. No one died.
Crowley never showed up at all. Neither did Death, who I thought would after his whole deal with Dean.
Chuck's narration felt like a deliberate waste of time so they could shave 10 minutes off the episode. Why would the angels have thought him to be a prophet (He was also implied to be killable by Zachariah) if he was really... God? Wouldn't they have sensed his power? The writers just resurrect him after half the season M.I.A. and make him shimmer out so we can infer that he's God? How weak...
There just wasn't really any climax. The past two seasons we're left thinking this one is gonna end in a huge climax, a character is going to die, things will change drastically... but instead the two main antagonists just fall into a hole. The end. To render any sense of loss surrounding Sam devoid - we're just gonna make him poof back into existence at the end!
Edit: Honestly, it just felt like they had filmed this episode a really long time ago, when this was supposed to be the last season. Then they went back to it, and instead of reworking it to not look like a series finale... they just slap in Sam appearing at the end and call it a day.