Controlling games just with a touch screen is, apparently, not an easy task. Not everybody is getting it right, it’s not only about the programming of the control, it’s also about the design. Direction and reaction speed are key issues to keep gamers playing. Here I have a few examples of touch screen iPhone game controllers.
EA got it right with The Simpsons Arcade interface. The design has a blue joystick that looks like a ball. The good thing is that this touchscreen joystick works perfectly without raising the finger from the screen, just moving it a little bit is enough to control Homer.
On the contrary, this Pacman version got an unhappy design solution. The touchscreen reacts slower than a real button, for this reason raising the finger should be avoided. This virtual joypad forces the user to raise the finger the whole time. As a result, moving the Pacman is slow and difficult.
Dig Dug, such a fun game… Unfortunately, it also got a touchscreen joypad that works very slowly. Most of the fun is gone.
The Commodore 64 emulator for iPhone has another virtual joystick. Probably, designers were focused on making the game look good; and it does look good. The joystick behaves almost like a real one; with it the user has to move the finger too far from the origin (central point) making the movements too slow. Unfortunately, controlling this game is a nightmare.
In my opinion, the reason iPhone games should not be designed to make the user raise the finger from the on-screen joystick is that it is difficult to hold the device. The iPhone is a great device but it lacks the ergonomic features of a real joystick. Maybe that’s why Marware released an [expensive] iPhone game grip.
It is easy to see the symbols on buttons, the contrast is good but having several functions working on one button could be confusing. From Rollei, we liked the way it navigates through pictures (unfortunately I can not show you that).
Having less buttons could make the camera look simple, but this graphic interface show us that this is not always true.
Here we noticed that it is very difficult to see the labels on buttons, the contrast is very bad.
One function for each button could be a good approach. I like the knob to turn the camera on and off, it’s impossible to confuse it with the shooting button.
The “Share” button might have good functionality, but honestly I don’t know what it does. What we discovered interviewing elderly people is that this group avoids pressing on buttons they don’t know what they are for.
This one has some buttons on the top that are almost impossible to see while taking pictures. “BS” seems to be something only Casio uses, we don’t know the meaning.
Painted buttons have great contrast! Unfortunately, it is very difficult to see what’s written on the other ones.
It seems that Casio likes wheels. Unfortunately, these wheels do not behave like real wheels.
There are some contrast issues here (on the buttons), but the most impressive things are the wheels. The one on the top is a real wheel the user can turn, the one on the bottom can not be turned.
These two models (above, below) got a touch screen. This is a risky approach, success depends mostly on how well the graphic interface is designed. For the one below, graving it properly could be quite complicated. 
This model got lots of functionality, buttons and wheels!
Flash position is good here, it’s difficult to place the finger on it.
The wheel could be an issue here and the buttons on top of the camera could not be seen when needed.
Some of the buttons in this camera seem to be part of this brand’s lexicon.
Painted buttons look great but the other ones have very bad contrast, I can imagine this being a big issue using the camera outdoors and even more for the elderly.
I wonder if labels like “AF/AE” are understandable to everybody. Should we carry the manual with us?
On many Canon cameras the wheel looks and works like a wheel, main function of it is to navigate through saved pictures. I like it a lot. 
Interesting design, but using buttons that don’t really look like buttons could be dangerous.
This model goes in the right direction. The wheel is great. Unfortunately the graphic interface is not that simple.
We noticed that symbols on this model are difficult to understand for many people, specially the ones on the top wheel.