Obviously you cannot use the codes without having the unit attached.
It's not so large that you couldn't carry it in a bag or jacket pocket, but it certainly makes your GBA/SP less portable.
Luckily, it doesn't interfere with your hands while you're playing.
After everything was set up I launched the program.
The simple interface shows installed codes, available codes from the site, and remaining space.
Management allows you to edit, add, and delete codes. Select Game is the important option, as it takes you to a list of games and cheats.
The version I received -- I assume that codes will be added to the base memory in future editions, so the number will probably grow -- came with 3,030 codes for 134 games.
After you insert the Action Replay and power up your handheld you are met by the main menu screen, from which you can choose Start Game, Select Game, Options, and Management.
Options include sound prompts, colors, and keyboard layout for entering codes manually.
I understand that handheld games can be just as complex and deserving of cheat/code devices, but they just don't come to mind. The Game Shark was for us Americans and the Action Replay was for you non-Americans.
(You could always import anything, of course, but officially that was the deal.) The two devices were essentially the same, despite some small tweaks and codes aimed at the respective markets.
We've reviewed both the PS2 and Game Cube versions of the Action Replay.