Just to comment on some points others brought up.
Service is easy. Most RV repair facilities can pull the units. Virtually any AC service company can affect needed repairs since all the parts are common to household units.
Noise, Inside the noise, like a roof top unit, is most noticeable at the return plenum. The basement air is not as load as a rooftop unit and there is only one return not two or three. The only other sound is the air through the ducts.
Bay storage, yep you lose a bay and in a smallish MH that could be an issue. To me that is simply a manner of efficient space utilization and not loading up on "STUFF". Pack rats never have enough storage anyway so that is a personal issue.
Running on 30A power is not different than roof units. Yeh, you can run both compressors but almost nothing else. On flip side, one compressor operation cools way better than running one roof top.
Are basement air units for everybody....probably not but you can see from the other posts that the majority of the negative comments are from folks who have a preconceived notion but no experience.