It was a pretty dynamic sound, and offered a solid grasp on detail and clarity, though not as strong as the best soundbars can go, if you spend a lot of month just on that, rather than having it bundled into your projector price.
But I was seriously impressed with the spatial sound and general home theater effect of the Atmos reproduction, and I don't think you'd need a soundbar in many cases, with one serious issue: bass.
Samsung has certainly tried to put bass into the Premiere 9 (it does claim two sub channels, after all!), but there's simply no physical way to put a really impactful subwoofer in a unit that large if you're also squeezing in a whole projector.