I like dynamic difficulty very much for the following reasons: - Seeing how difficult the parts of the song are in the top of the screen is nice to have - It looks better! In a song without DD I always feel uncomfortable because of that unesthetic straight line in the top - It's great when you want to get to know a new song withouht beeing overwhelmed by it's complexity. - Also, lately I found myself trying to fill the gaps in the notes (due to lower DD) on my own, just by listening. When I found out that I was right, that was really cool! When you really want to learn the whole of a song in the shortest possible time, of course in terms of effectivity it's best to set the difficulty to 100 % and accelarate every part on it's own until you play it perfectly. BUT there is an important difference between effectivity and motivation. - I feel like a lot of advanced players tend to forget what it feels like when you're a beginner. There is simply no chance you can play that song on 100 % difficulty - no way - it will just be frustrating. When you are at this stage, dynamic difficulty is super important for your motivation! When I played Rocksmith for the first time, I fired up "The Trooper" by Iron Maiden. And even though I would only play every 20th note or whatever, I felt like a superstar. It was awesome, just rocking along to the music. This feeling is extremely important for the motivation, and it's something that is unique to Rocksmith (you cannot to it with TABs)! The last point is my most important one, and the reason why I think everyone should include DD in their CDLCs.