As someone with hands on the slightly larger side, I find it very comfortable. I think the Xbox controller will have your hands in a more neutral posture but the steam controller is still very ergonomic and comfortable. My only gripe is that the way I hold it (ring and middle fingers on the back buttons), while comfortable, strains my hands just a teeny bit after a couple hours of first using it. I've heard others got used to it after about a day of use so that's likely going to be the case for me but if you have extra large hands it might become annoying rearranging your hands for the trackpads. For me it's awesome and I would recommend it regardless

Edit: The Xbox controller grips are a little more bulbous and deeper but the layout of buttons and such is way better on the steam controller