Spaghettim is one of the stalwarts of the Jerusalem dining scene. They also have restaurants in Tel Avia and Haifa. You can find their site (in Hebrew) at here. I am reviewing the Jerusalem location. The main attraction here is the beautiful patio dining in summer, but the quality food makes this a year-round destination.
The menu features 50 different types of pasta - from Bolognese to Ostrich meat. The selection is not Kosher and you can mix meat and dairy. This means Spaghettim is one of the few restaurants open in this area of Jerusalem on Shabbat, which makes it a big draw for tourists and/or non-observant Jews. The wine selection is good and reasonably priced and the desserts are fabulous (try the Fondant!).
We've eaten there many times and always had a good meal, with the service being at least acceptable. Spaghettim also has a non-smoking section, which is an additional draw. Many expat families favor the place, so they are used to children, too.