As far as the fights go? Most of them are pretty much what you'd expect, except that they 2-hour multiple times per fight. They have access to all the normal NM TP moves (like Wrath of _____, Doom, whatever), and much higher defense/evasion than we're used to post-Abyssea. Difficulty-wise, they're only slightly harder than fighting the old NMs at 75 would have been if the old NMs could 2-hour multiple times.
Look at the jobs for them on their pages
here, and they have the corresponding 2-hours. Sentinel's Scherzo, Earthen Armor, and White Mages are the best way to circumvent 2-hours that do a lot of AoE damage quickly (like Mijin and Astral Flow) or one-shotting TP moves (like bad Condemnations). You kill a little slower when you eat a Scherzo over a March, but you kill faster than if half your DDs had died.