I made this my afternoon coffee stop today, having seen the excellent reviews by other Yelpers.
To be honest, I don't see the big deal with Mos Mos. Sure, the "label your own cup" idea is cool, but it's a solution for a problem that really isn't a problem, and takes longer to figure out what label to put on your cup than it would to verbally give your order to one of the staff.
I ordered a medium latte which was very reasonably priced at $4, and it was made with care by the lovely staff who were very friendly. Although I didn't try any of the baked goods, they all looked very tasty indeed.
In terms of the coffee itself, I found that although the milk in my latte was steamed to perfection, I found the espresso itself to resemble those awful instant coffee pods you use at work - it just tasted a little on the artificial side.
I'll definitely drop by to try their brewed coffee as this is usually my preference, so maybe that will be better.