He was a writer who never wanted to be on the front line, and an idealist.
And yeah, he flaked out on his friends because he was scared shitless. he wasn't trained as a grunt, he was basically there working with intelligence and because he could speak French, and Hanks grabbed him and made him go along on this mission to save Ryan.
And after he flaked out and was devastated over his failure, he realized the captive he let go had rejoined the German army -- so he shot him point-blank and killed him. Apparently he learned his lesson about idealism in war and I don't think he'd flake out again, if he ever decided to hold a gun again. Like I said, he was there working with intelligence, not as a front line gunslinger like everyone else on the squad.
SOOOOO... that makes him much different than "OMG I SO MUCH HATE JAR JAR". Right?