Feels like everyone really brought their A-game this time! I guess Tofu Thalweg and Sky Sanctuary are the highlights for me, mainly for their explorative use of the larger scale maps can now be in UDMF. It's seriously impressive the variety of level gimmicks here considering how brand-new these mapping features are for SRB2. Radiant Reverie shows that automated gimmicks can actually be a joy in the right context, and Robotropolis Tunnels and Hoehle Denk Ich give an escape-sequence thrill I've never yet felt in SRB2. The only prominent issue I can think of would be the confusing backgrounds in Sunset Skyscraper, kept falling to my death trying to land on buildings in the background.
I haven't played all the levels yet but every level I've played so far are really good! (except twilight hill zone that one's borderline unbeatable on low end PCs cause of terrible/nonexistent optimisation)
In my humble opinion, this is the best oldc yet. EVERY map is a winner in my eyes. It's also great to see a such a diverse lineup of different design concepts for each map. I had a phenomenal time playing this pack and being part of it as well.