Osmow's probably has one of the best shawarmas around. Their sauces combined with hot sauce makes for a very tasteful shawarma that is only $5.75 with tax included. I usually go for medium spicyness but if you're new to the game, definitely start with mild.
TIMELINESS:
As the other yelpers have noted, if there is a line, don't even bother going in. Grab lunch elsewhere in the plaza. I've gone before and waited 15-20minutes just because they were so busy. At other times, I've gone just before the lunch rush (11:50AM) and waited no more than 5mins.
ATMOSPHERE:
Don't expect much, after all, you're only paying $6 for a wrap. This doesn't compare to a Paramount Fine Foods but its great for quick "fast food" meal.