The Lionheart LH9 series of pistols produces basically an upgraded and "Americanized" version of the DP-51/K-5. All three share the same trigger system, but are marketed under different names like "Fast Action and Triple Action, while Lionheart came up with Double Action Plus+". The concept of the triggers never changed, only the makers of the pistol has changed, and I believe that is where the names for the trigger action changed as well.
The way the trigger works is you load up the pistol first. After that, you will find that the hammer is cocked and to the rear. All you have to do is apply slight pressure on the hammer like your trying to push the hammer back up, because you are. After a little pressure is applied, the hammer will go back up on its own and you will notice that the trigger and trigger bar shift forward too. At this point you are ready to go and this is also how you decock the pistol. You can do this whole process with the safety on too if you are weary of it.
In my evaluation of this trigger, the initial pull on the trigger from Double Action Plus+ is a light one. It immediately snaps into the single action position and is ready, with little take-up, for you to take your first shot with a single action trigger. The entire poundage with this whole travel is around 6 pounds. That is a very attractive number for some people who dread the idea of a long weighted pull on the first shot. I found it to be a challenge at first to not get surprised when the pistol would go off so fast. I was used to the the long 8-10lb pull on my CZ P-07 for the first shot. I had to lay off the trigger until about 3/4 extension before touching the trigger because of how light it feels when I just go through my normal paced draw stroke. That being said, this is why you need to dry fire your guns and practice before shooting them.
When I was learning to adapt to this pistol, I began to understand what it could offer me. I like to stage my triggers on extension and break the shot once I verify that my sight picture is acceptable. It took some practice to dial it in with dry fire, but once i realized how to stage it without going through the full stroke, I found this trigger system to be quite well suited to my method of draw. I do not really see a better way to employee this trigger system than to stage it until I'm ready to break my shot.
I feel that people coming from striker fired pistols will find this trigger to be a more satisfying experience. Yes, you have the long pull, but it is 6lb and 2lb of it is used to bring the hammer to the rear and stage it in single action. Those used to traditional double action triggers may not find this trigger to be as rewarding if they like the heavy pull. Now If you like to lighten your double action, this is a good concept to check out. Overall, I feel that both types of preferences can be satisfied by this trigger concept. Give it a shot and you may just like it enough to prefer it.