Not exactly
The User Agent string is not the best solution for much of anything. Figure out the screen size and maybe do some adjustments there with loading different css files. Use some testing of particular features if needed in JavaScript. But please refrain from basing content on user agents if at all possible. This just leads to frustration for everyone, the user who has a new version of the browser gets the version of the site for the older browser and now it is displayed so horribly that it is unusable. Then the developer now has to thoroughly test every single version of every browser released for every single device, which isn't even possible.
