Well, this was a song I totally wasn't expecting to be anything more than your average chordfest, but hell, this really surprised me!
The first thing the song throws at you and what I consider to easily be the highlight of "Crawling In The Dark" is a crazy fun snake of hammer-ons that zig-zig all over the board broken up by a few strummed single notes too. It throws you in the deep end straight away, and you know what? I Lurve it!
Then the second half of the song kicks in, an insanely fast set of chord changes that switch erratically between two and three note chords, some of these pattern changes are very unusual, and some lesser experienced players may be thrown off by it, but stick at it, and you'll figure it out! It really keeps you on your toes, and throw this in with the aforementioned hammer-on section and you have a really engaging, relentless assault on the fingers.
There are a few changes to the formula throughout, mainly through the addition of fast gallops thrown in throughout the chordy parts. It's a welcome little addition, and makes a great chart even more fun and challenging.
Totally recommend this song too. One of the best modern songs on Guitar in my opinion, and one of the best of 2012.