Looks to be a great upgrade so far. I have not explored all the new features but there are two immediate advantages that justify the cost of the new version:
1. Capture One Pro 8 is seriously fast on a 2013 Mac Pro with D700s GPUs. There is a very noticeable speed increase over v7 on a test 30K image referenced catalog mainly of Nikon D800 RAW files.
2. The catalog can now see all my processed TIFFs (photoshop, exported for print etc.) making Capture One finally useable for asset management with my workflow. This was a previous complaint of mine and I am glad they have addressed it.
There must be some bugs, but so far the software is completely stable.