QWERTY BB10 = Superior gaming
So everyone just assumes: Z10 has a bigger screen, therefore its better for gaming. It has a similar aspect ratio to other platforms, so it'll get more games. The later is almost definitely true; however, does the lack of tactile input really lead to a better experience for a large number of games? I don't think so. A QWERTY device could easily give a better experience for a large number of games. Better productivity doesn't necessarily mean less effective entertainment :p.
The screen isn't "too small". Here is why: the Q10's screen measures in at 2.19" x 2.19". Here are dimensions of the screens on some portable consoles that have proven to be very successful. The GBA SP had 1.61"x2.41" and a screen on the Nintendo DS is 2.5"x 1.8". In both cases the Q10 has a taller screen and smaller width by 0.2-0.3". The area of the Q10's screen is larger in both cases so you will be getting a device with a larger screen found in popular dedicated gaming devices.
Tactile input. Enough said. Precision and control when you control games such as platformers. When the Z10 user runs into a bottomless pit due to the unreliable virtual joystick and buttons the awsd controls on the keyboard let you jump high into the air with complete precision. Your thumbs won't be blocking half the screen either. There's a reason why there's a constant stream of physical joysticks and game-pads coming out for the iphone: touch screens aren't precise!
Not all games would be better, in particular games that rely 100% on touch screen interaction with no reasonable qwerty mapping like Angry birds (touch and pull bird = game). In those cases a bigger screen is just plain better (game is touching. Bigger screen = more touching) but for traditional games/emulated games or games that require complete precision the Q10 would be plain better than a full touch phone.
So, when you are done typing your 50th consecutive email and decide to take a break by playing some Sonic 4, know full well that you are beating down your full touch toting buddies. :D