1) The Remodeling transaction helps you add new key figure and characteristics and handles historical data as well without much hassle. This is only available for infocubes in SAP BW 7x.
2) The BI accelerator (for now only for infocubes) helps in reducing query run time by almost a factor of 10 - 100.
3) Search functionality has improved. You can search any object you want to, which was not possible in SAP BW 3.5
4) The transformation replaces the transfer and update rules.
5) Introduction of Write-optmized DataStore Object in which does not have any change log and the requests do need any activation. The goal of such DSO is mainly to request its data with the Bex tools in order to provide queries at the raw data level..
6) One level of Transformation. This replaces the Transfer Rules and Update Rules.
7) Load in the PSA is a must in SAP BW 7x, which was optional in SAP BW 3.5 and data could be directly loaded to data targets.
8) In Infosets now you can include Infocubes as well.
9) Renamed ODS as DataStore Object (DSO).
10) Datawarehousing workbench replaces the administrator workbench.
11) New data flow capabilities such as Data Transfer Process (DTP), Real time data Acquisition
