I will list all the problems I can identify instead of just leaving a positive or negative review.
The controls are bad. It’s essentially a one button game, I should be able to press the same key to start as I would to jump.
The gradients look really bad for the clouds and sun.
It’s not obvious what the triangles are for. Clearly they give you points, but there is no sense of reward or objective.
The speed is constant, giving the user no sense of control.
All jumps are the same height, giving the user even less control.
The speed boost doesn’t feel like a bonus item. The sudden change coupled with the lack of control makes it seem like something to be avoided, not collected.
The timing is too difficult to master. The lack of control means most of the game is trial and error, which is not rewarding.
Sometimes there is not enough room for error.
Small mistakes mean instant death and pressing W near/over the edge does not result in a jump.
The clouds move at the same speed no matter how fast the player goes.
The player graphic style does not match the rest of the game.
The player’s legs don’t move fast enough and the animation is obviously off.
Look at the topic here on game immersion. You don’t need good graphics, but the awkward mix of art and unrealistic animations is too distracting.
Consider Mario and Canabalt as an example. In Mario, you don’t need to be centered on a block to jump off it. In Canabalt, the hit box is expanded for jumping and landing. You can actually miss a platform by a few pixels before a jump or landing and the game will correct it for you.
Adding a variable jump height or double jump feature would change a lot, but you probably should still pay attention to everything else I mentioned. Or add left/right arrows.