Shooting double action can be difficult or rather easy, it depends on how you do it.  With a revolver of course it is double-action only (DAO)--even though you can cock a traditional double-action (DA) revolver, it will fire DA-only as long as you so desire.  I don't consider a DA revolver difficult to shoot but I started handgun shooting doing nothing else--shooting DA revolvers in DA mode.   I consider that an advantage for shooting revolvers today, but not necessarily adaptable to shooting DA autos.  A revolver simply doesn't handle like an auto and vice versa.  Without meaning to oversimplify, a round gun and a square gun feel quite different, and thus handle differently.

The stated "problem" with traditional double action autos (TDA, also known as DA/SA), those which are intended to be fired first shot DA then subsequent shots single-action (SA), is that they require a trigger finger transition.  Frankly, this transition is difficult to accomplish smoothly.  It is also patently unnecessary. 

Old timers who learned to shoot decades ago were taught that the pad of the finger was ideal for SA shooting as it afforded the greatest feel, while the first or distal joint was ideal for DA shooting because it imparted greater leverage.  This is true but there is a down side in shooting with the pad of the finger when considering DA/SA guns. 

If there is a DA/SA feature on the gun you have three options.  First is to shoot the initial DA shot with the joint of your finger on the trigger, then change to the tip or pad of the finger for subsequent shots.  Depending on the gun and your hands this may range from inconvenient and slow to requiring an entire shift in grip.  To be avoided.

Second is to use the pad of your finger for every shot.  I had a double-action Colt revolver once that I shot this way because it had such a tremendous trigger reach I simply found that I couldn't get square behind the gun and still reach the trigger with my distal joint.  The down side of this method include the need for strong fingers--I do work with hand and finger exercisers; I believe it is necessary for handgunners--as well as the appearance of a heavier trigger pull than it actually is, because of lesser leverage.  This is not a method I would recommend unless absolutely required, and if it is required, the gun (or stock) simply doesn't fit you!  To be avoided.

The third method is obvious by now.  Use the distal joint for the first DA pull and then to continue with the same exact grip and finger placement for subsequent pulls.  The advantages are many.  First, you have no transition from pad to joint.  That transition baffled Cooper and it will baffle most shooters.  Second, the joint offers leverage that will imply a lighter trigger pull.  This is always a good thing.  It does work best with a pistol that has been engineered well enough not to have a horrendously heavy DA trigger and then a correspondingly light SA pull.  The best DA autos, and the SIG comes naturally to mind, do not feel terribly different when going from DA to SA, and I find them simple to shoot using the distal joint of my finger on the trigger for every shot. 

At this point the only difference is that pull weight is lessened, and after the first shot take-up never reverts to the original long throw.  You won't even notice this in rapid fire, and in fact you will learn not to allow the trigger to move any further forward than needed for reset, even though TDA designs normally have a fair amount of take-up in SA-mode compared to SAs or the Glock.  Simply skip the take-up.  Anyone who has mastered a 1911 or Glock pull will understand this intuitively.  It isn't much different--mechanically, but not mentally at least. 

At this point you might find that after mastery of the TDA auto you like to use your distal joint on on your SA-only triggers as well.  Maybe that is not a bad thing.