We've eaten at Arriba a few times now.  I really don't care for their food, and service is slow more often than not.  The first time we went we were there it took a good two hours!  And that's not because we're slow eaters.  We did stop in for happy hour last week though, and although their margaritas aren't the greatest, they're decent enough!  They ofter a 12 oz. house margarita for .99 or a 24 oz. grande for 4.99.  Why people would pay five times as much for a marg twice the size, I don't know.  We each had three .99 margs, ate the chips, salsa and bean dip and our bill came to 5.94.  $6 and I left with a full stomach and a buzz.  Nice!