No, seriously. I've read Hadfield's book, and I thought HE was happy to be in space, but they really did send a big kid up there with Massimino. He's just jazzed to be on the show, man.
This made it one of the more relatable astronaut bios I've read, because it's sort of hard to picture being Hadfield, since he's sort of really good at everything and secretly studied to be an astronaut since he was seven and just... who does that? Massimino, age seven, spent a couple weeks dressed in an astronaut costume his mom made playing with Astronaut!Snoopy and then reverted to his baseball obsession, only coming back to wanting to go to space after college, then accidentally applied to the wrong grad school. That's just... a lot more like something I'd do. It made me feel like the whole space thing was a bit more achievable.
The writing itself is definitely aimed at the YA crowd, but not dumbed down. There are a lot of gentle lessons about not trying to go it on your own, and not listening to fighter pilots when they try to teach you how to cheat the NASA eye exam, and "No matter what goes wrong in space, you can always make it worse" (the old Chris Craft if you don't know what to do, don't do anything axiom). Plus Massimino just thought space was cool, being an astronaut was cool, all the other astronauts were cool, and it was just fun to read about someone enjoying themselves that much, even through the rough patches like Columbia. He reads the book himself, and is funny and relatable.
This book also underlined a pet peeve I have about Apollo era books, which tend to conclude with a scathing attack on NASA after Apollo, to the tune of "We were great then, and we suck now." I'm not a fan of everything NASA has done in the past forty years, but I feel like the theme of the great space age essentially ending when Gene Cernan left the moon is... a bit hard to take. Maybe we haven't been to Mars yet, but there's been a lot of amazing work done in space since the Shuttle launched, and is still being done now.