Set Aside Some Time to Update
The iOS 9.0.1 update is small but you'll still want to set aside some time to install it. Maybe 20 to 30 minutes or so.
We haven't seen any major installation issues but there's always a chance that something will pop up during the download process that needs your attention. If you set aside some quiet time, you'll be able to deal with issues as they come.
You'll also be able to do a bit of testing after installing the update. You'll want to spend a few minutes going through your apps and the rest of the software to insure that there aren't any major problems that need your attention.