It's not bad. I really like the movement of the cube. It may be a bit awkward, but it's smoother than I'd expect from a first time Beta. Maybe focus a bit on making the movement feel more tight with the controls, and then move from there forward? I do like it, and there may be tweaks that are needed, but I think this could definitely go somewhere at least if you work on it hard enough!

are there only 4 levels?

I'm too tired to review this well but here we go, it's not like it's a bad game it's really just you're not nailing a few key things. The looks, platformers don't necessarily depend on beautiful scenery but it is really dull to look at, the core part of a platformer is the jumping really and the huge cube's jumps are slow and feel akward and I always get this sense when I jump i'm not going to reach the other side oh and this is personal opinion but this music loop needs to go lol. Like I said it's not a bad game, but it's not great either. I hope you make more games though, you just need experience

Don't submit test builds or "betas" to the portal please. Submit those to the Game Development forums instead.