Don't know never used one,BUT we had one for parts when I was in the service and it did one HELL of a good job on small jet engine parts. Don't know why it wouldnt work good on brass. Clened car carabutors really good.
Used one before I got my tumbler. It worked better than the vibratory but can only do smaller loads (~100 or so 45). If you don't mind the time than it will certainly meet your needs.
I use one and love it. I just bought the big one at Harbor Freight and it works really nice. The heater is awesome too! I actually use it to clean up two pistols that were underwater in the recent floods and they came out good as new. They both fit into it with no problem. I would guess it would hold 250+ 223 cases and probably 500 pistol cases.
For brass, I usually tumble it first and use the sonic cleaner after I've resized, trimmed and prepped the cases to get off the lube and clean the primer pockets and it works great. I never tried it without tumbling first because I usually run in batches and I don't usually deprime right after I tumble. I would assume water/solution would hang in the primer pockets if I sonic cleaned them and let them sit for a few days before I deprimed/resized.
It usually puts a better shine on the brass and cleans them up where the cases look new after I'm done. There is hardly any sign of powder residue in the case, flash hole and primer pocket. I put them into a dehydrator after I've rinsed in fresh water to dry them quickly and keep them from spotting up. They are dry enough to reload after a couple of hours but I usually don't get around to reloading them for a while just to be safe.