As far as I remember it was working well in 7 and 8 (deterministic and shows programs that you expect it to show). From 10 it started behaving erratically (same time it got binged but maybe unrelated).

It had problems in 8. I would frequently type my search term, see it was the number one result. I would then attempt to arrow or tab down and hit enter to launch that result. Between arrowing down and hitting enter, the result list would update/reorder and suddenly I'm launching some unknown program. Happened all the time.