I don't expect much out of Mexican food in London. The ingredients typically aren't fresh, the salsa is from a jar, the meat isn't chargrilled...the list goes on and on. And Tex Mex does not equal Mexican!!!
But Wahaca does a pretty good job. The menu is incredibly varied and you have a number of choices. It's a bit annoying that they crossed Mexican food with tapas, because I wanted to try all the types of meat but was informed that mixing and matching was not allowed. Ahhhh...I forgot I was in London, not Mexico, so customer service is optional.
Anyway, the food was all very good. Definitely the best guacamole I've had in town. The meat was all a bit too complicated but it was very good. What they need are some simple dishes to balance out the complicated marinated meat dishes. That said, the pibil was top-notch.
Service was a bit spotty but the server knew the menu inside and out. And the place was packed on a Monday night, so they're doing something right. Thus far it's the best Mexican I've found in London.