Venue 11 Pro (5130 32-bit)
I upgraded to WIndows 10. Everything seems fine EXCEPT that Bluetooth isn't available any longer. I upgraded the BIOS and Intel chipset firmware to the latest versions but it didn't resolve the problem.
The Bluetooth on/off toggle is not visible under Settings | Devices. The computer won't discover the wireless mouse that I was happily using with the tablet under Win 8.1.
Perhaps related is that the product support page for the tablet shows contradictory information:
"Windows 10 upgrade is available. Dell has tested this product to confirm that it can upgrade to WIndows 10"
and
"Windows 10 Operating System not supported for this device. Dell does not support the Windows 10 operating system with this device, Some Windows 10 compatible drivers may not be available on this page. View supported operating system or a list of Dell computers supported for Windows 10". The list contains my tablet.