Windows 10 64-bit upgrade was as smooth as butter. Everything is working for me so far and I didn't do anything special after the OS upgrade completed. It took a while, but was the easiest Windows upgrade yet.

Glad to have Windows 8 behind me. The Vista and ME of modern times...

It's a shame Roland couldn't be as forthcoming with a Windows10 driver for the UA25-EX. It's always been a solid performer on my laptop, now I either have to fork out for another audio interface or disconnect and lug my desktop interface with me when I need to go portable.
Just takes the edge off what could have been, what you call, a smooth upgrade. I think for every user that finds Windows10 an easy decision, there will be others that find the upgrade is not only not free, but not painless as well.
This is not a complaint. I have already made the decision to upgrade said interface, and I'm sure I'll be happy with the new OS, just not as fluid as some would have us believe.

"It's a shame Roland couldn't be as forthcoming with a Windows10 driver for the UA25-EX"
 
They're working on the UA25-EX driver.
 
http://www.roland.com/support/support_news/250024

To be sure, any upgrade is bound to adversely affect someone. And even similar systems might have different outcomes.

But I was happy to report that it went well for me. I hesitated until I saw some positive outcomes for other similar setups, so hopefully mine furthers the cause of confidence and expected probability of success.