I personally wasn't a big fan of the level system in The Witcher 3, and haven't been a big fan of NPCs, enemies and whatnot having numbered levels.
I'm a little bit of the opinion that numbered levels for the player character are a little outdated too, but, recognize and respect the roots of this game coming from a PnP RPG where numbered levels are indeed an integral part of the game.
I do, however, think, there should be some efforts in the gaming community by developers to explore other methods of player character advancement that feels a little more immersive organic and less "it's a game and you're THIS level".
Sadly, I don't have any decent spit-ball recommendations to even approach reworking a system that's starting to show it's age.
I'm also not too comfortable with developers rolling out experimental systems on big titles such as this, and think such experiments should get play tested in the wild with smaller games, perhaps even by an off-shoot studio name run by CDPR, or XYZ developer name, but distanced enough from the main house so that a spectacular failure doesn't kick them in the teeth.
If a new character advancement system is tried out on a small game, works, is received well, and even gets some good reviews, then, perhaps, develop that new system further.
As such, while I wasn't all-in on the level system we saw with the game-play demo, I was fine with it, and would have been content with it as it was.
I did take some issue with the double-jump. That just felt too video-gamey. I could see something like that being plausible in a low gravity environment where the character has a thruster pack or something, but, in Earth-normal gravity, eh, no.
Better bouncey cyber legs are great, and they should certainly help a character make amazing longer and higher than normal jumps, but, not double jumps.
Everything else, as I recall, was great, other than minor criticisms regarding things like enemy AI where the Maelstrom Gang with THOSE optics, should be able to see you through walls, underground, from space or something, and basically, if an enemy has certain cyberware, they should act like they have that cyberware and use it.
How are you going to sneak up on anyone that has a telescope on their head that can probably see through walls, especially when the whole gang is on high alert?
Granted, the demo was likely a bit scripted for the purposes of being exactly what a demo is ... a demonstration, thus, I suspect this is a minor criticism.
I was fine with the way guns appeared to work, and most everything else.