VPN on Android
VPN on Android has kind of been a sore subject since KitKat. I used to connect to L2TP on Mac OS X Server (snow leopard) from my phones as far back as Gingerbread, but with KitKat, L2TP became incompatible with Apple's implementation. That being said, PPTP works fine although being slightly less secure than L2TP. Android connects just fine to my Ubuntu Server PPTP, but no matter what I do I can not get get OpenSwan (Linux L2TP) to work outside my local LAN. Considering I have the EXACT same problem with OS X L2TP over the Internet but iOS devices can still manage to "phone home" to my L2TP server, I'm sure has something to do with my ISP considering L2TP an "enterprise" application and blocking my traffic, but iOS devices use some form of non-standard/undocumented L2TP.
I use VPN all the time for the simple fact that it provides a secure tunnel back home so I can grab files off my server, etc. Not only that, but it's a good way to provide at least some security when using public wifi. The thought of using public wifi without VPN gives me chills. It is disappointing that Android has deemed PPTP not secure enough to enable "always on vpn", which would tunnel 100% of your data through your VPN whenever a data connection (4G or WiFi) are available.