This riff serves as the common "heavy riff after the chorus" segment which usually ties the chorus back to a verse.
Rhythmically, it's a bit of a finger-twister. Each bar starts the same, and ends a little differently. Please recognize the tail-end 16th beat of beat 2, and how it's different from bar 19 to 20 - the second time, the sequence ends a little earlier.
Technique-wise, the main issue I've had with this riff is not letting the legato catch you off guard. Combined with alternate picking, the pull-offs found throughout will usually be the catalyst for confusion. Just like in the verse, we see a similar "always starting with a down stroke" picking style.
As mentioned in the introduction, "the simplicity of the notes is secondary to the powerful rhythmic syncopation between all instruments and the kick drum. Make sure to focus on this when playing to the backing track, as the exact rhythms will be mimiced with the kick - so if you aren't tight, this'll bring it out."
So whether you love this style of riffing or not, it's a great way of developing technique, understanding your own rhythmic development, and creating some awesome head-bob/bang-ing riffs.