The goodness of the food varies depending on what you order, as it does with every restaurant - it's really a hit or miss, but when it tastes good, it tastes REALLY good; this problem diminishes the more you visit as you discover which meals you like and which to avoid. I recommend the pasta with red sauce and garlic bread with vegan butter. The amount of food you receive also varies, and not just slightly - I have been served way too much to eat in one sitting (not a bad thing at all!) or way too little for the price. I love how they serve their cola in cute jars, and that they serve their peanut butter and jelly sandwiches with chips and salsa. Their ice cream and brownies are delicious, and so far Pneumatic has been the only restaurant I've come across that offers vegan deserts.
The atmosphere is nice, it's just slightly cramped but not enough to be a bother once you get seated. The smell is lovely and the decorations are so interesting that the short wait for your food goes by even faster while you admire the eccentric art, the walls and ceiling are literally covered in it, and they change all the time. The music is always so good and just loud enough - it's just a cozy, great place to hang out. Long after finishing a meal it remains a good environment to chill and talk (if it's not busy).
My experiences with the staff have all been good, they may not be too overzealous in comparison to most waiters/waitresses in other restaurants but they have never been rude and I don't mind their casual attitude, though friends of mine have occasionally described them as pretentious or too laid back.
Their few cons (difficult to find, cramped, employees that can be too casual) are completely overshadowed by their delicious food and they don't take away from the fact that's it's just a fun place to be.