So Windows 7 has been around in Release To Manufacturer (RTM) for since August 14, 2009.
Many have been using it in production since then. In fact, many have been using in Production since it was still in beta/release candidate form.
I have been using it for 1 month.
It is so much better than Vista and XP that it would take a novel to describe all the ways it is better. Most of them are simple things.
Anyway, please post comments on how long you have been using Windows 7 and why you like it.