"the movie was alright in a technical point of view"
Technically speaking...well let me repeat some of the things I said:
As to music, John Williams (gasp!) does something OTHER than repeat the Potter theme over and over again. He throws in different stuff, even jazz.
As for tired CGI cliches---the rollercoaster POV in the Quidditch game, the way the magical creatures are presented well-lit and front-and-center (because they're so expensive)--you don't see any of that here. No, they don't look any more solid or realistic than in the previous Potter movies, but like with the hippogriff, Cuaron distracts you with the creature's performance. It may not look fully real, but it acts so wild and frightening it persuades you that it's real. With the other creatures, we see them through the heads of fellow students, or off-center in the screen, or quickly and casually in a handheld shot...in other words, they're shot and treated like the actors and props and sets, and no more special than they. This gives them equal status and (strangely enough) makes them seem more real.
Several times Cuaron moves through glass and walls from one room to another. It's a nice little transition, and usually in your standard Hollywood movie the director finds a computer cable or air duct to justify this move; Cuaron just passes through wood and stone and glass, period. More, he seems to have thought out the transition; when the camera passes through glass, for example, it's like ice melting and solidifying again. And sometimes he ends the shot with a little flourish, a movement to suggest it's really a camera and not a computer doing it.
None of this really cures the flat CGI look, or makes me finally love CGI. But it's interesting that Cuaron works against the CGI effects and tries as much as possible to make them part of the the film's look and style.
It's all in the mind, and Cuaron understood this. Columbus--eh, you could fill a Cray supercomputer with what he doesn't understand about filmmaking.
As to costumes--I love it that they dress more casually; it brings them closer to our world, and that's important. In Columbus' films, the costumes look like they were taken out of their boxes the day they started shooting. In Cuaron's film, they look like the characters have been wearing them for a while...
As for cinematography--did I say pure poetry? Radcliffe notes in an interview how fond Cuaron is of long shots and a camera that moves in or trucks around. Cuaron's more stylish, among his many other virtues. He just doesn't shoot the scene as if it were a poster; he treats it as a space to dive into and explore.
More, he lends an emotional tone to the visual style. When he moves the camera or angles it, or lights the characters and sets just so, it's to make you feel something. As for Columbus--well, what I said about him and supercomputers.