Each of those keys corresponds to the most common letter that would be pressed with the same finger when touch-typing on a traditional QWERTY keyboard (also QWERTZ and AZERTY). Together with the space and shift keys, the home keys of ASETNIOP make up more than 65% of total keystrokes.
The idea is that once you've learned the name of the keyboard, you've also learned the home keys in their proper order.
For most of the keys, including punctuation, each chord includes the original finger that would be used to type that key on a traditional keyboard. For example, W includes the left ring finger, and U includes the right index finger. Common letters (H, R, D, L) are assigned to easy chords, and less common ones (X, Z) are assigned to harder ones.
Not at all! Producing a letter with ASETNIOP actually happens when you release the key (rather than on the downward stroke), so as long as you press both keys down before releasing either of them, it will register the chord properly. And even when you mess up, there's an autocorrect feature to smooth things out.
There are some different tricks - I personally used some mnemonic devices to learn them together as pairs. For example, R and H are the lifeblood of the system (RH factor). DL is Down Low. CU Later. FM radio. J and G are phonetically similar. Y and V are visually similar. But mostly it's the same as with a traditional keyboard - if you use it regularly, the keystrokes will become second nature and you'll stop having to think about it.
It hasn't for me. I type at around 100 wpm on a regular keyboard and about 80 wpm on ASETNIOP and have never had any issues transitioning between the two. And if you don't already know how to touch-type, mastering ASETNIOP might actually make learning to touch-type on a traditional keyboard easier!
It varies. One user reported reaching speeds of 50+ wpm after five days of practice. Another user managed to hit 37 wpm after practicing for less than half an hour. Most users won't pick things up quite so quickly, but you can expect to reach about 30 wpm after a couple hours of practice.
You can switch to a numbers and symbols layout by pressing a special combination (the "devil horns" combination of chords for F and M). On touchscreen devices, you can also produce numbers and symbols without changing layouts by swiping upwards or downwards on the keys instead of tapping them.
Nope. The system is designed based on ten buttons, because you have ten fingers. Adding extra buttons would defeat the purpose.
That's only because Apple requires it. They are very strict about that.
Learning ASETNIOP requires a commitment of time and energy. It's a very worthwhile commitment, but much like learning to touch-type, it has to be self-driven. My hope is that people who are willing to spend a few bucks on it will want to get a return on their investment, and will use that as motivation to climb the learning curve. Think of it as a kickstarter with instant gratification.
"Easier" methods (like swiping/gliding keyboards) are the equivalent of a xylophone. You can understand the concept instantly and develop skills very quickly, but it's got a limited ceiling. ASETNIOP is more like a guitar. It takes a lot more time to learn, but you can do so much more. And because it's based on a simple principle (ten fingers, ten input points), ASETNIOP will continue to be relevant as technology and input systems evolve.
There are alternative layouts for these, with different home keys (AOEIHTNS and ARSTNEIO, respectively). The principles are the same (chords include the finger that would normally be used for these keys on a traditional keyboard) and many of the numbers, symbols, and punctuation keys are unchanged from ASETNIOP.
In the original layout for numbers and symbols, the 5 and 6 were pressed with the thumbs and the shift and space keys were thumb-pinky chords. In practice, it turned out to be a disaster. It's much easier to remember that 5 and 6 are chords than to start mucking around with how the shift and space keys (which you use much more frequently) work.
It's probably better to think of the shift key as more of an "iterator" key, that iterates different things depending on the situation. If you hold it down while pressing other keys, it will work the same way it does on a traditional keyboard - as a standard shift key. Otherwise, at the beginning of a word, it's a sticky shift key. Pressing it twice will activate the caps lock. In the middle of a word it will iterate through the different predictive choices. If there are no choices (i.e. the predictive feature is disabled or you're typing something it doesn't recognize), it will revert to its sticky shift behavior. At the end of a word, if there are other forms of the word containing accented characters, it will iterate through those.
For efficiency purposes, if a potential predicted word is only one base letter away from what you've already typed (say, you've typed "ca" and the predicted word is "cat") it won't show it as a prediction. This is because it would take just as many keystrokes (possibly more) to iterate to the predicted word than to just type it normally.
There are a few different methods for dealing with accented characters. In cases where the only proper form of the word includes an accent (such as café) the autocorrect will handle it. In cases where there are multiple forms (such as resume and résumé), once the word is type you can iterate through potential options using the shift key. For words that aren't in the dictionary, you can hold down the left (or right) ring finger and tap the appropriate key on the opposite side of the keyboard three times to activate the accent, which will then be added to the next character you type.
There's an optional setting for that. When it's active, if you type an exclamation point or a question mark at the beginning of a word it will automatically invert them for you.
On Android, just press all ten fingers down at the same time and it will recalibrate the tracking circles to where your fingertips are. On iOS, long-press the layout change (#123) button and it will recenter them.