Well, I did post a comparison yesterday at the German boards... I'll translate it here
As I've seen both systems, I can compare them pretty good.
1. CPU: The Pandora is significantly faster than the WIZ.
For Homebrew-Games that's irrelevant. It will be relevant for more complex applications or emulators.
2. Display: Pandora has a higher resolution, WIZ is - thanks to OLED - much brighter.
If you're outside very often and don't need a higher resolution (i.e. for playing some games, etc.), the WIZ is well better for you in that aspect.
If you need a higher resolution (i.e. for internet, etc.) but are using it inside a room most of the time, the Pandora is way better suited.
3. Size and design: The Pandora is a bit bigger and thicker, the WIZ is smaller and more compact. If you're on the go a lot and are looking basically for a small MP3 player with additional functions like a movie player or game player, the WIZ does suit you well.
If your pocket is a bit bigger and you like to check your eMails or internet or play more complex games, it's the Pandora you need.
4. Mobile Office: Well, without keyboard or Internet, you can't do much with the WIZ. It has a planner and an alarm included, if that's all you need, you're fine. Need WiFi, Internet or office apps? Well, that's when you need a Pandora.
5. Some more infos:
Pandora has TV OUT and USB Host, you can easily connect mouse, keyboard, joystick and TV. Not possible with the WIZ, it doesn't have TV OUT. The WIZ clearly is meant to be a true mobile handheld device.
GPH plans to support Homebrew and Homebrew-Devs, they also want to offer a platform for homebrew devs to sell their games for a cheap price. They also plan to release low-budget commercial games.
Pandora will have the dev fund. If it sells well, there surely will be commercial games.
The WIZ is cheaper, which might also be an aspect for some of you.
6. Games and Applications
On the Pandora, you can expect other applications and games. FreeCiv, Battle for Wesnoth or LinCity NG for example wouldn't make much sense on a WIZ because of the low resolution.
But the WIZ will be very good for Arcade- or Puzzlegames.
Console emulators should work fine on both devices, with DOSBox and Amiga the Pandora is better as you have a keyboard, higher CPU power and a better resolution.
--> Conclusion:
The WIZ is definately the better system for casual gamers or gamers who love to play classic console-like games (be it original homebrew games or emulated games), up to the PSX-Standard. It's better to use outside than any other gaming handheld I've seen yet because of the OLED screen.
The Pandora is a more fully fledged system which offers all of the above (except OLED), but also includes additional features. This means, besides Internet and office stuff, you can also play more PC-like games which make use of a keyboard, mouse or higher resolution. But it's also more expensive.
So, you don't need all those additional functions the Pandora offers? The WIZ is fine for you.
You want to access internet and love high-res and keyboards? Get a Pandora.