Great little location, so get one of the outside tables in the summer like we did and watch the world go by. The interior looked nice and cozy for colder weather. Had a wonderful rucola pizza that was perfect. They have Kostritzer beer. Very reasonable prices.
Note that there can be some confusion regarding the "annex seating" which is across the street, I think in a shaded churchyard. The seating is shared with a crepes place, which is also just next door to the pizzeria. Make sure you are sitting in the right area. We had to move from the "crepes seating" which was fine because we lucked into one of the little tables you can see in the photo above right by the door of the pizzeria.
After the pizza, there is good Italian gelato cafe in the square behind the pizzeria. In fact, Weimar seems to have a really good selection of gelato places, perhaps almost as many as in neighboring Erfurt.