A bit of background...
I have been reading comics since I was a nipper back in '69 and have now moved on to the point were I sell them for a living. I am therefore predisposed to like just about anything that's realised on the big screen.
That being said, I defy you to find a more enjoyable film this year. It's not the best film of the year, but it sure as hell leaves you with the biggest grin when you wander out again into the night air. Some of the flaws are obvious, but none of them are fatal. Yes, the tone is light in so many places, sometimes at the expense of tension, but when it HAS to go full-on metal, I think Ragnarok delivers.
Blanchett, Goldblum, Hiddleston and, surprisingly, Hemsworth, deliver great performances, hamming it up when needed, but never descending into parody.
One point regarding Immigrant Song...it's used twice, I think, but very differently. Early doors, it's used when a very brash, arrogant Thor is doing his thing and winning the day as he fully expected he would do. The second time, though, it really does mean something...everything's on the line at that point and the words 'Valhalla I am coming' are probably where his head is at.