It works fine in Windows 8.1. I just looked, and it doesn't look like I had to make any compatibility changes to get it to work. However, last night I upgraded to Windows 10 and Freelancer didn't work afterward.
I tried reinstalling Freelancer. No change.
I tried the compatibility wizard in Windows 10, and I tried several different manual settings such as Windows 7 compat. I'm starting it as Admin. Freelancer starts but quits before any graphics come up. I don't see any event log entries.
I thought at first it was because of a driver problem with the GeForce GT 740M on my Toshiba Satellite S55, however, I rolled back to Win8.1 and was able to play again. After playing I noticed I have the same driver issue in 8.1. (I rolled back the driver in 8.1 and now it is ok. No yellow triangle. But that wasn't an option in windows 10.) But anyway, I believe in 8.1 I was playing fine even with the driver issue.
I'm back on 8.1 but I want to re-try Windows 10 shortly. I'm sure the driver issue will be fixed soon.