The ink is expensive, the prints can bet stunning or they can be crap, sometimes it is all over the map, the shirts need to be pre-treated, the machines have a very short lifespan, less than 5 years before they are obsolete, the white ink is really expensive, they are slow, it takes a certain amount of skill to operate them.
On the bright side you can do full photo prints as one offs, mixed media, more than just shirts such as canvas and other higher end materials.
Yes I owned one, now I do not and don't plan to get back into it as our customer base is mostly Rhinestones, embroidery and sports teams