I've just now gotten into Retro's Donkey Kong Country Returns, and so far, I agree with everything Chad Concelmo said in his review. It's awesome. Playing the game has me desperate to see Retro return to the Metroid series. The brilliant level design, the ingeniously placed hidden areas, the need to use your multiple abilities to fully explore levels, and the plentiful forms of new and fascinating wildlife all make Donkey Kong Country Returns a classic, and I'd love Retro use those same element to create a new 2D, home console Metroid game.
This concept art for Retro's Metroid Prime only has me more excited about the idea. From the looks of it, the game originally called for a battle against a six armed ice baboon, and a slightly smaller, spikier version of Kraid from Super Metroid. Can you picture those battles in a new Metroid game that has the graphic fidelity of Metroid Prime, the camera angle of Donkey Kong Country Returns, and the gameplay of Super Metroid?