Seriously? My Lumia 830 is every bit as stable as every other phone, Windows or otherwise, I've owned, which is to say it is 100% rock-solid and hasn't crashed or randomly rebooted even once since I bought it last October. It's running 8.10.14219.341 and I really couldn't be happier with it. Maybe you need to reset yours and start again?
If you go through the bugs thread random reboots is probably the most mentioned one. Turns out full Denim fixes it for most people, so I have to wait for that. Although with one of the Lumia 830s I owned it was happening an inordinate number of times a day and turned out to be a hardware defect.