I've been to a Soho Joe a few times. The pizzas and burgers are consistently good, especially for the price you pay (note: price advised by Trip Advisor is out of date, all pizzas are £9 and burgers £9 to £12).
Nice atmosphere, whether there as a couple or a big group.
Prices are very reasonable given the area and given the quality of the food. Nice big, tasty pizzas with enough toppings. Decent sized burgers, nice fries. Drinks also reasonably priced. Neither me nor any of my friends have had a pasta dish so no comments from me on the pasta.
Personally, the thing that keeps me coming back is the beautiful lady working front of house. She is beautiful, friendly, confident, and keeps the restaurant ticking over.
Great venue for a bite to eat pre-night out in Soho or central London.
It's worth reiterating other reviewers' comments: This place is cash only, remember to have some with you.