I used to work at Subway too.
As has been said before, very repetitive and boring - and LOTS of cleaning.
The only positives for me were free drinks (from the machine, not bottles) whenever we wanted; a free six inch or footlong (depending on how long you worked - but I don't really like Subway so not really a perk); and whatever cookies were left over at the end of the day.
Also the customers can get very bitchy because of the whole "make your own sandwhich" thing. They yell at you for putting a drop too much of sauce, and one lady whos fat kids ordered double cheese, meat and bacon yelled at me for "robbing her blind" - why in my right mind would I want to rob anyone, I don't get any of the money!
What also frustrates me is that they implemented this whole "rewards" scheme a month before I left (I was there 15 months) where you get certain rewards for selling above the expected sandwhiches - like a drink from the fridge, movie tickets etc. Just before I left!
And finally one crappy thing about "my" Subway, was that I was never asked to take on responsibility of opening/closing till etc (managerial stuff) even though, except for one other girl, I had been there since the store opened. Even when I expressed interest the manager/owner never taught me.
And to add insult to injury, one of the final things that made me quit, some of my last shifts I was "supervised" by a guy who had been there for two weeks!!! I was telling him how to do stuff all the time, but just because the manager had shown him how to do all the managerial stuff, he was "in charge"!
DON'T WORK AT SUBWAY!