I went to Real Taco in Harvard Sq. yesterday and I was terribly dissapointed.
I expected crowd, and there was a huge one, but sadly the food and service have a long way to go.
Some problems -
1) The music was blasting so you couldn't hear orders being called.
2) Two of the guys preparing food threw out just as many burritos and tacos as I saw them manage to get out the door.
3) My goodness were my tacos lousy. I ordered real tacos with fish. One of them actually had 3 tortillas. The lettuce wasn't very fresh and there was no salsa.
I think in about 2 months this place will turn around and be as good as it's sister, but for now I would avoid it. Big crowds, lots of hype, and untrained staff make for a frustrating cheap treat.