Believe me - it's the best taco in town.
I've been really loyal to them since I started having their taco a year ago (long before they moved to 69 Kensington Ave.). Their Baja fish taco is especially amazingly done - however, you shall just try everything else in the store. The daily special is highly recommended as well since they make that with the freshest ingredients they have.
Oh, also, get the homemade special juice. You will not regret of paying that 3 dollars, believe me. (My favorite is the mint watermelon juice....damn good)
One thing tho - the tacos are not that filling to me. Seven Lives is a shop about the flavor - it doesn't make you that full.