Before these d-pad patches, many have searched for the answer to that very question, often ending with the following result:
Then they ought to have searched better. These are far more refined but other ones have existed for quite a while, as have guides to hack in support in the first place (though such a thing does require so not inconsiderable hacking skills).
my only point was don't bash touch only control based games there's plenty of them that are great and have great game play value, the kirby series besides Kirby Super Star Ultra, The wario ware games ninja gaiden, Pac N' Roll, Pokemon Dash, Pokemon Trozei, Arkanoid DS. There's more I just can't think of them right now
I was not trying to lump anybody in this thread in with those from the original threads -- in said threads they were saying things like you shouldn't be doing this, the creators made the game and you should be playing it like that.
Touch controls are useful, and useful for more than just having some of the better menu systems outside something I have a mouse and keyboard with. The trouble comes with many a DS game having awful touch things crowbarred in because Nintendo said they had to (not sure about later but early on they had to have a touch element), and even worse in some cases touch controls made to the exclusion of dpad controls.
I have had great times with touch games on the DS (
http://gbatemp.net/threads/links-to-various-gbatemp-features-over-the-years.352851/ should feature no small amount of them and I genuinely do like Doodle Hex), however I am going to have to join the others and say I am not so sure it works for directly controlled platform/action like Zelda. They made it functional and more or less playable but this makes it better.
You say Kirby and that is a fun game, however it is not direct control as much as giving you a few seconds in which you can also correct yourself. Also arkanoid had that paddle controller.
Touch controls
Things they are good at
Normal game menus
As a keyboard of sorts.
Camera control, even full analogue style camera control.
Allowing me to play ScummVM (it took far too long for adventure games to start appearing in earnest).
In game map selection (I want to zoom in on this rectangle I just made)
In game reasonably complex menus -- no crazy button combos or hitting A nine times, just tap or drag.
Tap this spot quickly and accurately (think the multiplayer tile matching speed game in NSMB)
Simple gestures/accuracy following (think trauma center)
RTS games
Turn based games (think advance wars)
Rhythm games
As a simplistic alternative to left and right/one axis movement, or as some kind of crude analogue controls. These can even be for things that can be described as twitch games.
As little more than a glorified button, however you are then able to turn it very quickly into more complex controls without having to remove a hand from the buttons or dpad (not that left handed people were well catered to).
As a screen abstraction. Those games where I control a crosshair seen on the upper screen but on the touchscreen, does well if it is the sort of game that needs it.
Related to the above three would be I once played a shmup (veggy world I think) that fired when you touched the screen but moved the crosshairs using the middle of the screen as the middle of the circle for the fire (dpad then did movement). Worked quite well actually.
I even like some... jank I guess. I once played a game based on a girl's book series* (and I think it was in French as well) and it had a driving section in. The touch screen did gears, steering and something else. It was bastard hard but it did half amuse.
*not that I feel any need to justify anything but it was the "latest ten games" part of a review.
Not good
Games that were traditionally played with need for timing on a joystick or dpad.
Complex/accurate gestures, think the first Castlevania seals or don't if you don't want the memories to come back.
Full analogue joystick emulation. No Mario 64 port that is not acceptable, good effort though.
Touch was way more than just a net positive and we will probably see it on everything that even hopes to compete until games get pumped directly into our brains, or someone figures out how to track our fingers/read our thoughts. However to ignore the limitations and examples thereof would be bad.