I'm migrating a v6.x installation to Series 7.
Series 7 IWR appears to be much improved from v6.
Publishing reports is easier with no need to "Shuttle" reports before publishing.
The online portal is now integrated with Cognos Upfront (same portal PowerPlay uses). Most deployment options are now set through the online portal instead of a seperate Admin tool (including report schedules, output type, burst reports, etc.).
There is now functionality for report versions. Reports on the portal can be set to maintain multiple version (depending on prompt values, user classes, etc.).
If you're familiar with the old IWR (v6 and prior), this is a major improvement. Migration from earlier releases, however, is not easy.
HTH,
Justin