QlikView is a powerful visualization and data discovery tool, and works well when you have the right hardware to support it. I've seen the users getting excited about the tool, and the usage ever expanding in most places, provided the KPIs available are relevant.
The tool offers much more capability than simple dashboarding - the natve qvd file formats are excellent if you want to do lots of data cleansing and massaging. Due to this reason, clients can avoid having a separate database license for DWH (please note that QV is not a full fledged DWH, though it supports the most wanted functionalities).
QlikView works out to be the best cost effective when the number of users vary between 50 to 250. Users above or below may have its impact on the pricing per user.
In a nutshell, it is a great product to create leadership dashboards setup for any organization size.