As I work with SAP based clients, here's what I see:
SAP BI, like any data warehouse environment, is great for static reporting of well-known and centrally staged data and information. It is by its nature, for the most part, IT driven. Companies will use normally use SAP BI for "corporate reporting" of basic summarized information. Its limits, generally speaking, are that it usually does not incorporate departmental data from external sources and systems, therefore limiting a single integrated view across organizations and processes. It is also relatively inflexible when an end user wants to answer the ad hoc "question of the day" that an IT DBA hadn't or couldn't have anticipated and built a cube for.
QlikView is virtually always added as a complementary solution to SAP BI. So first, it's not either/or, its both. QlikView is everything that SAP BI is not: user driven, able to drill down to the transactional level of detail from any direction or combination, flexible enough to quickly be modified to answer ad hoc questions (if not available with a few clicks) and can readily incorporate virtually any non-SAP BI staged data into a single, integrated view. It's also very easy to build dashboards representing higher level metrics.
I wish I could share some client examples, but don't have permission to at this time. Here are some published examples though:
and a recorded webinar:
Also, you can send me a message to learn more.
I hope that helps!
I think from an it architecture perspective the best solution is to build qlikview dashboards based on solide sap bw/bi datamodel ! In my personal view this is the best fit. Even if i appreciate qlikview and it's functionality i personally believe that it's showing it's strength in frontend design and the fast qccess to huge amounts of data but not setting up a corporate data warehounsing structure.