I liked their character designs in Halo 3 and ODST, but looked like shit in Reach. Now in terms of actual lore, the Jiralhanae show to be pretty simple-minded and Brutes like Maccabeus and Lydus were more than likely a rarity amongst them. They weren't "acting" devoted to the Great Journey, they truly believed in it, and when the Prophets and their centralized leadership vanished, the entire species collapsed; even though the Sangheili were locked in their own civil war, they never put more emphasis on that than, say, food and were still able to gain an upper-hand against the Jiralhanae. Speaking of food, we also know from dialogue in Halo 3 (Crow's Nest if i'm not mistaken) that they don't always wait for their enemies to die before they begin eating. Let's not forget that they're likely called savage because they're the only Covenant race that will literally drop its gun in a middle of a fight and charge with the intention of tearing you apart with it's bare hands. Now with all of that being said, they are very similar to the Elites which is more than likely why a rivalry has been present between them for so long. Regardless, the Jiralhanae have a bad rap because they kinda put themselves in that corner. War is a lot more important to them than anything else and even if the Arbiter manages to salvage negotiations with Lydus (which he likely will) whose to say that other Chieftains of other powerful packs would be so willing? If an allied faction does rise from the Jiralhanae, it'll only be a small number compared to the overwhelming number of traditional, anti-Human/Sangheili tribes.