The keypad and its effects

I just saw a post in MoMo-NY about a new mobile keypad concept called "fastap". Aside from the numeric keys, it features a key for each letter in the ABC in the corners of the numeric keys (However, it does add another row of 3 keys at the bottom).

This keypad is featured on the new LG AX490 phone (in the picture to the left). You can read the full article here.

Anyway, what seems to be another standard handset innovation has more effect that you might think. Improving the human interface (and especially the keyboard/keypad) is a major issue to the success of mobile applications.

And it has to be done wisely, meaning without affecting the phone's total size, since the bigger the phone is the less mobile it is. You don't want to take away the one thing mobile phones are good at.... Or as I have written before: If it doesn't fit in your pocket without competing for space with your private parts - it is not a mainstream device... (This colorful rule of thumb is taken from my post about mobile blogging).

Fastap's solution seems to affect the size, but reasonably, the question is whether it is actually comfortable, and that I will be able to address only after actually testing it.

SonyEricsson has another solution I first saw in 3GSM, in which each key is actually two keys: when you tap it to the left you get one letter, and when you tap it to the right you get another. I tested this one and it is very comfortable, but on the other hand it does add 2 columns of keys (so the keypad is 5x4 and not 3x4) making the device something between a handset and a PDA, which doesn't really do the trick. This keypad is featured for example in their P1 phone.

Anyway, it is obvious that the form factor here is critical to the usage of mobile applications, so whoever finds the best one, will do good not only to himself but also the entire industry.