Other is the temporary file cached/stored in your phone, this is the other storage bug that people complain on windows phone 8 that file size keep expanding. Some manufacturer even come out a temporary solution by releasing own apps to try to fix it.

Amber/GDR2 update had fixed this issue, but how good the condition of fixing it is different on each phone.
WP8 is still a OS that still under developing by Microsoft, so expect some of the Android's features will not found on WP8 (notification center, for example). OS is closed OS (not much customization can be done), OS is less hardware demanding (won't lag)

Wechat, whatapps, line, most of the basic social apps is available, except instagram (only had unofficial one, recently got one is quite good), youtube (google and microsoft had bad blood, so no official one by youtube, even microsoft developed apps had been block by google, but had plenty of unofficial apps with good function). Also no google service apps (google+, google maps) on WP8.

Waze is on beta testing before acquired by google, but since google had bad blood with microsoft, don't expect google will officially release on WP8 in neartime.

apps and Games also not much compare to android (total apps+games: 170,000 only), but some developer slowly migrate to WP8 after release their apps on ios + android.

Don't had candy crush, subway surfer, minion rush (minion rush is coming soon, announced by Gameloft)

For user that switch from android to WP8:
http://www.windowsphone.com/en-US/how-to/w...o-windows-phone