They are rubbery, strongly egg-y in their flavor and let's just say the frosting puts the "butter" in buttercream.
I'm bummed about the texture, and I can't figure out what I did wrong. Probably overmixed the batter, even though I used cake flour. (However, the instructions weren't very helpful..."mix until batter has a curdled appearance". Well, maybe that is helpful except I didn't know what it meant. Curdled milk?)
But the flavor was the real disappointment. I followed the yellow cake recipe from "The Best Recipe" by America's Test Kitchen, which has a LOT of butter in it. So much that the cupcakes are actually a bit greasy. And you can really taste the eggs.
And the frosting? I've had "real" buttercream frosting before and it definitely had a better texture than what I made. Perhaps I didn't beat it long enough because it's not very fluffy and it's not even very sweet. It really does taste just like butter with some sugar and lime (I didn't have any lemon) mixed in. If there is a difference between handheld mixers and stand mixers in the amount of time needed to achieve the results, I wish a recipe would note that. The cake recipe did, but the frosting recipe (from the same book) didn't.