The second manga I've ever read. To put it in two words: It's alright.
Story: It had direction and it had a goal so yeah the plot line was good I knew where I as a reader would be going after the first few chapters.
Art: Not great, all the characters look pretty similar to me.
Character: Yes large variety, but no development I guess? One shot, so yes very short and probably reason why there was little character change except for in the end the protagonist realizes there's more to life than being a astronaut. (If you don't get the joke read the manga)
Enjoyment: So yes good for a light read I would have probably have kept on reading just because of it's plot line if it had been longer so the ending in my opinion was abrupt.
So a 6 overall hope this was useful, happy manga reading!