Getter Robo is a classic Manga/Anime Legends, back in the day Anime wasn't all Waifu's Boring Protagonists and basic Tropes, but a Iconic franchises in Japan. Getter isn't only a Anime with bad flaws but a inspirations. Arc may look underrated or might not be popular by newer fans in 2021, but the other Series, the original 1973 Series, Shin Getter Robo/ Getter Robo Armageddon, Shin Getter Robo vs Neo Getter Robo and New Getter Robo are different. If you want to watch something else rather than Arc I highly recommend to give Armageddon a try, Getter Robo is a Old School Classic that debut beforeany Anime popular anime at the moment.