SSFIV; Upgrading to a fightstick after a year and a half on the pad
It sucks!!!
I am too used to the PS3 controller to do this. First of all on the PS3 controller you do not have to hit every single direction accurately to execute a move. Because a persons thumb already cover half the pad chances are when you press back on the pad you are going to be pressing back, down back and down on it. It allows for consistent execution of moves, but has potential for throwing in random surprises. I have on many occasions thrown out accident double quarter-circle-forward (qcf) supers or ended up with shoryukens instead of fireballs. In high end combat such accidents can be fatal.
The other problem is that I have synchronized my thumb to the timing for those annoying 1-frame combos, e.g. Guiles lp into mp. Now I have to get the timing right all over again with my fingers.
On the other hand doing long chains and some of the harder combos in street fighter are much easier. Especially combos that rely on focus-cancel such as Akuma’s Shoryuken cancel into 3-hit fireball.
In the end you will find all your fancy moves and tricks that you have learned on the pad failing miserably online. Only your deep understanding on zoning the opponent and controlling distant will be keeping you alive.
If you don’t want to spend the same amount of time training on the pad as on the stick, then I suggest staying away. However, because the stick does make it easier to pull of focus-cancels in the end it will improve your game considerably.