I found the science authentic, and well thought out, and the alien and his tech and culture realistic (even if they were entirely too similar to our own to be believable. But I also found much in it that I didn't care for.

Like way too much science fiction, the expertise, ingenuity and heroics of the lead characters are just not believable, he's just too clever, and his alien counterpart too cutesy for my taste. Perhaps I'm prejudiced, but I've always suspected that the gulf between species would be insurmountable, no matter how much the two representatives were motivated to work together for their common good.

I didn't read "The Martian", but I did see the film, and I have pretty much the same criticisms (and admirations) for that work. Maybe I'm too much influenced by post-modern literary fashion and theory, but the situations encountered in science fiction too often rely on people (or ETs) who are way too clever and determined and entirely too noble compared to the sentient organisms I know, myself included. Maybe its the Heinlein legacy. Oh yes, I know humans are capable of enormous empathy and ingenuity and sometimes they are magnificent in crisis; but they often succeed in spite of their faults, not because of their virtues. And even the most superb efforts are often accompanied by multiple errors and mistakes and profound foolishness. Even the finest among us can be idiots, or lazy, or cowardly or selfish, particularly under pressure. The truly heroic accounts, like Shackleton and Bligh, are indeed inspiring, but I suspect they often leave out the real horror they had to overcome, and the toll it took on them. For every Apollo 13 there is a Custer's Last Stand.

Maybe I'm just a hopeless cynic, and if you wish to castigate me for that I probably will deserve much of your criticism; people sometimes do act heroically and brilliantly. I just tend to be skeptical about the basic sci-fi protagonist, who is perceptive, dedicated, fearless and hyper-competent, all the time. I also recognize modern literary fashion tends to be pessimistic and too often focuses on our neuroses and not our triumphs. Still, I tend to subscribe to the old WWII infantryman's observation; "A hero is just a coward who got cornered."