Sieb's is like a lot of other "Irish" places in Pittsburgh. Predictable pub decor and menu-- except for the odd inclusion of a few pasta dishes which are not worth your time or money. The dining room itself is quite small and often the service is appallingly bad. Sometimes it is ok but I've never experienced the great time described in some of the other reviews here. Several times I have had to ask for silverware, and then it arrived dirty. Waitstaff will ignore you to talk to other guests. One night there was a guy with two little kids in one of the booths, and the Staff was gushing all over them and ignoring the rest of the customers. I assume either he was family, or related to one of the employees, but-- really-- he could have come visiting sometime other than a busy Saturday night.
The Irish Menu presents the usual suspects, none of them stellar. My sig/oth likes their burgers, and it is in the neighbrhood, so I've had to settle on a couple of usual items to order when he chooses this place. The Irish Stew in a Bread Bowl, and the Chicken Pie are both tasty if you don't feel like cooking. I really like to order soup but, after a few tries here, gave up due to its always coming out lukewarm. I ordered the Rueben sandwich once and had to spit half of it out due to the corn beef being unchewable. Prices are just what you'd expect at a neighborhood place (@$45.00 with beers and tip for two). We've been going to this place for several years now, and no one has ever even intimated that they recognize us or appreciate our business.
If it's Irish you're after, Mullaney's in the Strip is more "authentic," and Finnegan's Wake on the Northshore is more fun. This place is ok if you stick to the bar and don't expect too much more than a sandwich and a beer.