At least give a reason why?
I thought there wasn't a need to elaborate, as it's what I consider to be typical LBP faults.
The first of which is the slow floaty movement, which doesn't get better by integrating Vita touchscreen gimmicks in the design. Secondly, they are using 2.5D perspective and if you wanna go somewhere with that, you have exploit the .5D part of it by having level design that takes advantage of the perspective. Having levels rotate, focus on background/foreground interaction and stuff like that. It won't be as precise as a regular 2D platformer - 2.5D never is - but at least you're getting something out of it that couldn't be done in 2D and you need that, to replace the precision lost by going 2.5D.
What LBP Vita did, in what little I saw of it, was use 2.5D but keeping it static like a regular 2D game. Losing the precision and gaining (little/)nothing (worthwhile).
And to top it off the leveldesign was simply uninspired. That might have come from it being user-created content(didn't see that much, so not sure), but it still didn't inspire confidence. What makes for interesting platform game design is not set in stone, but I'll give a few examples:
Take Super Mario 3D land and notice how something like tightrope walking is integrated into the game. First you encounter it and it's just a rope. Then it becomes a rope with a slow moving enemy later on and still further on two moving enemies or faster ones. That's a typical layered structure. Introduce something simple and add an extra layer to the same thing later on.
You can do cinematic platforming where the controls and obstacles are made in such a way, as to make certain that failing is quite difficult. The intent here is not to challenge a player in the same way as a Mario game, but to define, to visualize or to build up the narrative or coming/current events.
Another thing could be small mechanical twists in player perception or orientation. Rocket Knight Adventures lava level where you have to navigate platforms reflected in the lava is one such example. Or you could require the player to put himself in danger to hurt an enemy. Sonic & Knuckles Flying Battery Zone boss would be an example of that.
The point being that there are many different ways to create interesting mechanics and LBP Vita didn't show any of them a few touchscreen gimmicks notwithstanding.
All this might change in the final game or in other parts of the movie, but what little I saw had floaty movement, used the perspective for little interesting and didn't exhibit any exciting mechanics. It didn't look fun playing.