I do like the presentation of those later emerald-hunting stages. And I'm glad I'm not the only one who climbed all the way to the top of Meteor Herd to drill-dive all the way back down! Thank you Cam for validating my weird side. =D
But I gotta be honest - I feel like the emerald-hunting levels, the way they were designed, make actually hunting for emeralds a chore. It's a "conflicting prime directives" kind of thing. On one hand, you've got a wide-open sandbox to screw around in at your leisure, which is good and fun! But on the other hand, you have to search for specific things within that sandbox, on a time limit if you're going for score. Practice makes perfect, yes, but first-timers, bandwagoners, and "eff"ing casuals will always complain about these levels.
I do have one legit complaint, though, with the first Rouge level. I had to chase down the last emerald in the water tunnel that you have to ride on a turtle to get through or else it pushes you out. You know what I'm talking about, where you have to time getting on the turtle just right so the emerald runs into you as you're passing through? Figuring out the timing on that BS almost made me late for work. >=(