It almost gives off the vibes of a 20th-century Western-made Saturday morning cartoon (except that for some reason the MC’s relationship with his mecha-ude reminds me of the one between the lead in Kill La Kill and her seifuku). I’m not quite sure why—maybe it’s the lack of any real moral ambiguity? Anyway, many of those could not do cool or edgy to save their lives.
The Trigun Maximum manga wasn’t finished at the time the series aired, so their endings are unrelated. The last 4-5 episodes of the anime are complete originals. (There were two different manga series, and I think the original Trigun manga had more of the goofy-villain-of-the-week stuff, while Maximum, which picked up where the first series left off, was more serious.)