Installing in Program Files vs. Appdata

What are the benefits and downsides of installing an application in the user's AppData directory?

I assume that installing in AppData will let users in restricted environments be able to install and use the application.

One of the benefits of installing to Program Files is that is exactly where the user expects it to go. Usually users go here first to look where the program is installed. The biggest downside is that the user needs administrative privileges, which isn't always required by the program.

You are correct in assuming installing to AppData will let restricted users install and use the application. It also will follow the user around on network systems, allowing them to have access to the program from any machine they log into with the same account. This is also a downside however since it means 2 or 3 users on a machine will have 2 or 3 versions of it installed.

Google installs its products to AppData, which is great since it can then be installed by any user (including at schools where the computers are stuck with IE6 or something).

You should use AppData for any configuration, or program files that will change with the program. I personally prefer installing programs to Program Files, because that's where users assume it will be installed, and it requires admin permissions, which is usually set for a reason, and abiding by those permissions is just nice for an app to do. Ultimately it's up to you, but the default should probably just be Program Files.

Generally appears that the "Appdata" directory equates to the user software directory someone might notice using Linux systems; hadn't paid too much attention to the shift from Program Files directory installations toward the increasingly popular Appdata folder, but it slowly dawns on me.

Thread is a bit old, but relevant considering that Windows is still pretty active; Program Files installations are mostly for your touchy apps --the ones that you will want a bit more access control over like maintenance and security apps. Your Appdata folder is pretty much any other "user" specific soft like media players, text editors; etc. The "administrator" of a Windows installation will also benefit from using appdata for "normal" software along the same lines as not installing software in the root directory while administering a Linux, Mac or BSD system.