After Kingdom Hearts didnt work, i assumed everything since then also doesnt work. However, i read otherwise with stuff like patchwork heroes working. At this point, using the latest firmware, what does NOT work?
Kingdom Hearts has AP protection other games just use 6.xx encryption keys so most games (as long as they don't have AP protection) should work on 5.50 GEN-D3 just fine until Sony releases a firmware update with new encryption keys and games start using those keys.
There's a simpel Decrypter program that even lets you play games on m33. I got an 5.00 m33-6 and every game works just fine for me ^^. Except the above list from MisterCraig, but I don't play that many JP games anyway.
I don't know if everything as in actually EVERYTHING works.
The only thing i saw a bit glitchy was one small meaningless thing on the menu where you change your Fighting Moves in the Stances Stats...
It was unreadable. But other than that nothing comes to mind.
Unlimited Memory Internet Browser
Basically anything that is made by a singular person or by anyone/group who isn't an official Organization is home-brew. So say you use CWCheat, its Home-brew. But so is the PSPTube that I use and the Unlimited Memory Browser I use. You can see how PSP home-brew makes a huge difference and is quite nice to have.