Devhook is a PSPfirmware emulator. It can emulate up to version 3.11. But, custom firmwares, which are easier, safer, and better to customize, while still being able to play homebrew and the newest games, are making Devhook obsolete. So, in lamer terms, Devhook is a homebrew application that runs a firmware from the memory stick, rather than the onboard flash, causing the PSP to think it is running 3.11, thus giving the player the ability to play UMD games up to 3.11 as well as being able to play homebrew, when Devhook is "turned off". However, some users have foolishly tried to emulate 3.11 and upgrade that firmware to 3.30, allowing them to play even higher version games. But what they don't realize is that the flasher doesn't know they are using Devhook, and writes to the flash. Since the person is "running" 3.11, the flasher thinks they have 3.11 on the onboard flash, too. So, it writes the wrong files in the wrong places (because the Sony flashers don't actually format the flash0, they just overwrite existing files), resulting in a semi-brick. These things, combined with the fact Devhook is very complicated to use, and Custom Firmwares are easier, and even have a recovery function, have made Devhook scarcely used anymore.
In other words, forget Devhook. Go with custom firmware.
