I have worked with SAP Business Warehouse since 1998, doing mostly "frontend" development and support for BW reporting. BW has changed a lot since the early days (v 1.0A!), mostly for the better.
We are currently on SAP BW 3.5, with plans to upgrade to SAP NW 2004s BI 7.1 after it is released, probably in mid-2008. We have always had many BEx Analyzer users, but in the past year or so have started to migrate them over to Web reports on SAP Enterprise Portal.