I've been a loyal patron of King Slice for at least 10 if not 15 years now and it never gets old. The only place where I've had a better pizza was in Italy itself. Every time I'm in the neighborhood I make sure I stop by for a slice.
The one thing I want to point out too is that I've only seen them increase prices once over the 10 or so years and somewhere in the range of 10-25cent.
In terms of off days for slices, I've had that happen occasionally though very infrequently. For the most part the slices are great.
Also try their pasta and soups (tomato soup is amazing).