I've been here numerous times since they opened. DiBella's is one of the best subs you can get in Pgh, to say nothing of dahntahn.
There's a large assortments of subs and meats - capicola, corned beef, chicken philly, genoa salami, ham, etc. I've had everything from the dagwood to the old fashioned, philly cheesesteak to buffalo chicken. All quite delicious and a good balance between meat, cheese and toppings.
And you can get them hot! Me does not like cold subs.
The wait can be a little long during the lunch rush but I think they do a pretty good job considering the volume. The order takers are pretty friendly.
Overall, this is one of my favorites in market square, esp. getting to-go when the weather is nice and you can sit outside and people-watch while eating.