One contact mentioned he averaged 1500-1700 views a day before the switch, to about 400 a day since. Others have seen similar drops. I normally don't get many views, but its been pretty meager since the change.
I think there are two reasons for this. One, everyone's most recent photo now shows up large on all their contact's home pages. Why click on the photostream when you're already seeing the most recent picture in large size? I know I haven't clicked onto more than one or two other people's streams since the switch. I can't be the only one.
Secondly, the endless scroll doesn't work. On my home page, I can scroll and scroll to see new pics from my contacts, but eventually I get to the bottom where the thing comes on and says "Loading more pictures". Then when they load, there's a gap. I have to scroll back UP to see what I've missed! It does this on all three computers I use regularly. Not being a fan of the endless scroll in the first place, its just maddening to have to scroll back up to see what I've missed. So I just don't. End result - less photo views.