I visited this restaurant on the basis of a recommendation by a fellow Guide, ashford. Sadly I didn't manage to pick a night when Sir Paul McCartney dropped in, but aside from that everything ashford promised came true. The food was excellent.
Hope Street is up near the University and the Catholic Cathedral. It is a bit of a walk from the town centre, and the streets don't always look to friendly, so you may want to take a cab. It is worth it, however. It is a good area for food. The nearby No. 60 is also highly recommended.
Speaking as a resident of California, I find most British-based Mexican restaurants a disappointment. El Macho is an exception. I must admit that their plate of nachos for two would be served for one in an American restaurant, but portions are generally much smaller in the UK. Besides, British nachos are better because British cheese has so much more flavour. The main course, when it came, was very tasty. No punches were pulled on the spice front. I went with a large group (11, I think), and everyone was very happy with their food. The service was good too.
Some friends of mine who had been to the restaurant before advised us that the Margheritas are not good. We avoided them. But they have Mexican beer, which is perfectly OK. Overall, I really liked this place, and if I go back to Liverpool I will make a point of seeking it out.