First off, let me just say that the 2 bartenders, Sam and John, that are usually there Thursday - Saturday are phenomenal. My company goes there for some happy hour sake bombing every now and then for about a year now. We always get excellent service, they serve you up fast and friendly and the drink selection is like you'd find at any high end bar. Plus they're fun to chat with and they make the bar come alive with conversation and fun. The bar upstairs also has a karaoke machine, which is a lot of laughs/fun after a bunch of sake bombs.
Second of all, the sushi is the best I've had in Philadelphia. Mizu sushi and POD sushi are ok, but Fuji Mountain really makes the sushi the way it's supposed to be made. Everything tempura is fantastic here. They have a great selection of maki and nigiri. I particularly like their hamachi rolls.
If you want to eat mouth watering sushi, go here. If you want to have an awesome bar experience, go here. One of my favorite places in Philadelphia and well worth the prices.
Cheers!
Pros: Bartenders, Service, Sushi, Ambience, Karaoke
Cons: Can get crowded, can be pricey