Went to DelTaco for the very first time this week and boy was I ever hungry. So, I ordered the "Macho" sized combo. Whoa, was that ever a mistake. My first clue should have been that it was a MACHO combo, which I am clearly not. :) The fries came in a large soft drink cup and the macho sized soda was as big as my head- took 2 hands to pick it up. My main advice, stick to the small!
As for the food, I had the soft chicken tacos which were pretty good. I wouldn't say they compare to an actualy sit-down mexican restraunt, but were good considering I only paid a couple bucks and was eating within a few minutes of ordering. I'd go back again if I needed some tacos in a hurry.
Side note: Don't use the stuffed animal grabber machine... it stole my money :)