Photobook is a useful tool for managing various user data, displaying it and providing complex permissioning on who can view what. It was recently implemented at Sloan and I did an initial port to postgres.
Complex survey has cool functionality that lets you define questions where the answers are stored outside the survey package, like in the users table. This allows you to slowly gather demographic information about your users in the context of other surveys.
So Photobook's strengths are display and permissioning.
Complex Survey's strengths are ability to collect information at different times in the context of a survey and use the information already gathered in future surveys.
Based on reading the survey docs it looks pretty easy to use them together by defining complex survey questions that refer to the photobook views. This is good news for anyone who wants to build sophisticated user information collection and display right now.
Please note that this is programmer only territory, you can't customize photobook from the UI yet and its current configuration is very Sloan specific. Also photobook is new, it uses the CR and CMS automatic form building and is generally not for the faint of heart.
I haven't used complex survey yet so no comments on how easy/hard that is. The docs make it look pretty easy.
So thats the good news. The bad news is that this is not where we want to be long term. Yes you can recreate a photobook question in complex survey but if its a select list question you will end up repeating all the data in two unconnected places in the database. Not good for maintenance of your select lists which is one of the strengths of Photobook.
Photobook (or what will evolve from it which probably should be called Profile) needs easier mechanisms for creating questions and determining who should be asked which questions and when. That is what Complex Survey already does well.
Survey itself is undergoing a major rewrite and will probably move to greater use of the CR, which should move it closer to Photobook.
Profile/Photobook programmers and Survey programmers please take a look at the other and lets set a long term goal of moving these packages closer together.