I popped in the Williams Collection disc for PS3 over the weekend after playing this and was actually kinda disappointed to see so many things in it that Pinball Arcade doesn't have. The flippers are way more responsive and faster and the plunger pulls back nice and smooth, more camera options, a nice playfield pan at the start... the DMDs also seem to be less "fudgy," and even quicker--makes it seem almost like they have some kinda blur filter on the Pinball Arcade. I also miss being able to poke around the "virtual arcade" like we could in the old game. That is to say nothing of the challenge mode (which I suppose just has yet to be implemented).
On the other hand, PA's physics blow the old game away, and the HDR lighting is like a revelation compared to the William's collection. The tables also seem more oddly constructed in the old game, and are much improved in PA.
PA occupies kind of a weird space right now, I guess... not quite "beta" software but still notably janky in certain aspects. If there's any game that can only benefit from continued updates it's this. I just pray they put the support behind it that it needs going forward to really surpass Williams Collection.