I told my British fiance about this place after reading this thread tonight, and he immediately said we HAD TO GO NOW. (He LOVES Chipotle, has the t-shirts and everything!) Even though it was 8pm, we live in South London, and the place closes at 9 on Sundays, we ran to the tube and made it there about 8:50pm after sprinting all over the immediate area around the tube trying to find it - the sign wasn't lit up and it was dark! I think the staff thought we were a bit mad as we turned up out of breath, sprinting inside, and with huge grins on our faces!
He had a steak burrito and I had a chicken burrito and they were SO good - a bit colder than Chipotle's, but I think that is because it was the end of the night. It tastes about about as similar to Chipotle as you can get - I think people who aren't as addicted as he is wouldn't notice much of a difference at all! Just be careful to state how much of each thing you want in your taco/burrito - the staff aren't as carefully trained in good proportions as they are at Chipotle. The assembly line production, tortilla warmers, etc are the same - its wonderful! We will be driving through North London tomorrow evening and he wants to go back to try the tacos - I think this will be his new fave restaurant in all of London.
Just go and try it. Seriously, this place is amazing. The hype is worth it.