Eh. I didn't like it. I didn't care much about the setup – the cake was baked by peripheral characters to enter a contest we're not invested in and their competition was a host of characters we'd never met before. (Well, okay. We met pony Joe. But we don't know anything about him.) If this had been the wedding cake for next week's royal wedding, I might have cared; there's a personal connection there. Ditto if Pinkie herself had baked it so there was something personal riding on the outcome. I had sort of suspected I wouldn't care based on the synopses, but I kept waiting for the usual brilliant detail this show does that would sell me on a silly premise. Alas it never came.
Anyway, like "The Mysterious Mare Do Well," the episode hinges on the reveal at the end, and also like TMMDW, what we find out makes no bucking sense. I don't buy that those three would do what they did, and I really don't buy that the chefs would do what they did in response.
I did enjoy the small details, as always: the parody short films "explaining" Pinkie's deductions were great, and the opening sequence of trying to get the cake to the train was a lot of fun (though it does raise the question of how Big Mac would have so much trouble carrying a cake when he was able to drag an entire house behind him in "Hearts and Hooves Day.") But man cannot live on gags alone; cap it all off with a moral that has next to nothing to do with the rest of the episode, and you've got a solid C at best.