There were some bugs in the demo that made it genuinely difficult to create a working spaceship. Though I *was* able to get to orbit in the demo.

It's a simulator, so getting a working spacecraft and learning how to fly it is something that's going to involve some work and some trial and error. I don't recall if the demo had a tutorial section or not, I know the full version of the game has a tutorial section. I completely skipped the tutorial and did fine, but I'm told that the tutorial contained important information, such as, you have to press T to turn on the SAS system to keep the spaceship from spinning out of control and breaking apart. Also, looking at the tutorial sections on the KSP wiki can help.

The full version is quite advanced even though it's still at only alpha 0.22 at this time. The full version has many more parts available to build spaceships with, and entirely new sections to the game. But if you were frustrated by the demo, I don't think the full version will help that.

The demo cinched it for me because I like the idea of tinkering with a spaceship design, and having to correct design flaws that make the ship fail, and have to start over again. I like that. Some people would find that frustrating, and I get that. I don't think this game is for that category of folk. You might possibly be in that category.