Whether the difficulty level is too low or not may depend on what you want this game to be. I know that, just enjoying it as some quick-and-simple fun, I enjoyed it.
If I may, I have two points of critique:
First, I had little indication of where I was supposed to go. This was especially troublesome at the start of the game: I was still figuring out what I was supposed to do, and the view was quite close to the rocket, leaving me able to see only a little distance around it.
Second, the collision detection around the giant trees encountered early on was a bit unforgiving: in places I could "crash" into one of them without apparently coming into contact. This felt a little frustrating.
All that said, let me note conversely that I rather liked the handling of the rocket: the controls were responsive, and the rocket's acceleration was low enough to suggest weight while high enough that it didn't feel ponderous. In short, the rocket controlled well, I think! ^_^
And as I said, I overall enjoyed my time with this game. ^_^