I went to Gallipoli Bazaar for a friends birthday and we had a great time. As some of the others have noted, there are three separate Gallipoli locations on Upper Street, but I am talking about the main restaurant one, not the cafes.
The space is a bit narrow but absolutely crammed with atmosphere and whimsical features. Although we were a big group and thus at a long table (which they were happy to increase the size of when more friends arrived), I admired the two-person 'tables' that seemed more like massive serving trays with legs. Very neat looking.
Since we were a big group we opted for the set meal which was an absolute torrent of small dishes - a large variety of veggie (hummus, beans, potatoes, salad) and non-veg (really yummy lamb skewers, a tasty chicken dish) flavours. The food came quickly, and it just kept coming! By the time it stopped arriving, every last square inch of our table was covered with one bowl or another full of tasty Turkish goodness.
The servers were helpful, although possibly could have been a bit more attentive. Still, they had a fun time with our group it was clear, and even played a song for the birthday girl, who promptly stood up and improvised a little belly dance. It was a real fun night, and I could imagine myself ducking in to one of the more informal cafes sometime for a quick lunch as well.