Lovely, and delicious. :)

The real reason why Derpy keeps delivering things wrong or messed up or damaged.

Mmm… Its perfect. But had to comper to the Pinkie one- bw/color. Just know you asked for opinions other way i would not say anything.
 
Pussy looks great. The ponut could be more deeply set but more plump so it dosynt apper so flat. Line on it look much better but still could use little adjustments. You overdid a bit on the “shine”- i think- but maybe its just the b&w.  
Boobs look just as @AstrumSpark  
say they are the max size that dosynt look out of place the nipples could be a little bigger and the breasts smaller.
 
I love this drawing as it is but you ask for suggestions so here they are. :) love ya man!

Really good! And it’s great the crotch boobs aren’t oversized (they are close to maximum size that can be done with ponies).  
Some people like to slap regular chest boobs there, and think it’s sexy. XD Maybe to some people it is… but definitely not close to how equine anatomy works.