Programs and drivers are a case by case issue. Everyone will be different.
Big developers like Adobe, Google, Mozilla etc will have been working on Windows 10 compatibility for months now and their programs should work from the get go. Smaller developers might not be up to speed meaning you have stability issues or worse the program flat out doesn't work until they release an update to fix compatibility, which could be months down the line.
Determine what programs are important to you and do some research if they are Windows 10 compatible yet.
And while you're at it do some research on hardware drivers. If you can't find Windows 10 compatible drivers for your hardware it's probably not a good idea to upgrade yet.
Also check out drivers for peripherals like Printers. I upgraded to Win 8 on release day and it was near 2 months before I could use the scanner on my printer because HP were slow in releasing new drivers.