The depth TC Electronic has gone to create the whole TonePrint concept and then apply it to each one of their pedals still seems incredible to me, and has worked great for me personally.
Regarding the Flashback 2 X4 specifically, I find all the basic algorithms usable, and when it comes to the range of delay sounds that can be achieved through TonePrints, the possibilities are literally endless. You don't really need to dig that deep and get lost in seas you cannot swim though, since that there are so many great TonePrints already created by a lot of artists and players, that you probably won't even have to open the TonePrint editor not even once. If you want to finetune a few of those and bring it closer to your needs though, or if you are experienced at programming sound effects and you want to create a totally personal pedal from the get-go, the TP editor will open an interesting new world for you. For the rest of us lazy guitarists out there, what's already available is more than enough, since that the five self-explanatory controls of the front panel make it the simplest mega-delay to operate.
As for the differences between the 1st and 2nd version of the Flashback X4, the newer version has 6 storable presets instead of 3, 6 TonePrint slots instead of 4, a dedicated Subdivisions control, the Bypass and Kill-Dry switches easily accessible on the front side of the pedal (and not inside), and of course the MASH function, which is basically a way to apply expression functionality to each one of the 6 presets (another clever and useful innovation). All of them very welcome features.
The whole Flashback X4 experience is like having thousands of delay pedals at your disposal and use only the few that you need, and in the simplest way possible. So, to sum it up, this unit checks all the boxes in what makes a great and forward thinking delay unit, and is by far the most important pedal of my whole board.
P.S.: My favorite TonePrints are the Andy Martin Echoplex 2 and the Pat Cuchanan Crazy Tape Delay. Give them a try, you won't be disappointed. ;)