Like the above have said, if it's good resin, it's very easy. Easier than metal, actually. Good resin carves and files better than metal or plastic, and you can reposition it by dunking it in simmering water, bending it, then dunking it in cold water. IMO good resin is the best of the three major materials (metal, resin, plastic).
However, bad resin is the worst of the three major materials. Cheap crappy formulas are brittle, and can splinter or crumble when carving. Resin that's got inert fillers/extenders mixed into it is impossible to bend with heat, which affects both ones ability to mod, and more damningly, one's ability to correct warped castings. There's also A LOT of caster, especially in the gaming market, who don't really know how to cast with it, so even with good companies you see a lot of bad molding/casting technique that effects the quality and useability of the castings. There's well regarded manufacturers on these very forums who are guilty of these things in my experience.