My opinion, not yours, agree, disagree!
POSTIVES
Heartfelt: The episode cares more about the relationships between Homer, Carl, Lenny and Moe, than the jokes, which is a risk but I love it, I would love to see more episodes like this, but of course you know we don't (from the latest seasons).
Storyline: The one thing the Simpsons have been struggling since season 15, has been getting a good decent, consistent storyline throughout an episode. In somewhat ways a lot of the newer episodes ending's of the storyline's have to be rushed, but unlike this episode, it explores more about the Characters and the past in slow manner, instead of rushing, which I think is really good.
Music: I love the music in this episode, performed by Sigur Ros, it gives an extra spice about the storyline in Iceland, as the band are Icelandic.
Colourful: The one thing a lot critics agree on about the newer Simpsons, that it is more colourful and smoother than ever before, which I think it looks great as well.
NEGATIVES
Storyline: Again the storyline is great but, it just feels like a one hit wonder story, it feels like it was a great idea at the time but now, we'll there's nothing.
Jokes: Again the jokes are alright, nothing too great or nothing special to remember.
OVERALL
To finish off, this is one of the best and consistent episodes of the 24th season of the Simpsons. A true heartfelt episode about what Friends are really meant to each other.
QUOTE FROM THE SHOW
" Forget it Carl, it's World War II all over again, America kicks Iceland's".