Going on from dirge's sentiments, I don't like gimmicks where it overwhelms or detracts from the Transformer as an action figure/play-toy. And I'm sure many of us felt the same as kids... look at the Battlechargers from G1... how much did you enjoy playing with those toys as a kid compared to other TFs that weren't as dominated by their gimmicks.

There's nothing inherently wrong with gimmicks, it's how they're executed in the toy and how much of the toy's playability which is of paramount importance for a child... I hated(still hate) toys that I cannot have fun playing with, and to me - even as a child - that meant action figure role-playing. Gimmicks are fine with me so long as they don't detract from being to play with the toy.