Great little independent shop. It's a high school hang out during the day. Doesn't have long hours, so it is not good for a satiating late-night snack: it would be long closed by that point. Good but not great pizza. However, if you want just a slice, it's basically the place to go to in the West Junction area along Dundas Street.
The atmosphere can be described as "a dive", with one table for eating, making this strictly a take out food place. Good service, and good prices for the size of pizza you get.
A better tasting pizza slice can be had at King Slice on Bloor Street, but that's almost 3 km away. So for the price and convenience, Dundas Pizza is your only option in the area.
It does accept debit, but charges a fee if the order is below $20. Most slices are under $4. It also serves chicken wings and kebobs as well.