Generally speaking, direct to garment printing can produce a very high quality and durable print. We advise our customers at GreatApparelForYou.com to turn the shirts inside-out and wash them in cold water. That's nothing new, though, as it's the same advice for screen-printing.
DTG printing does pose certain challenges, such as printing on dark garments. Generally, we've been successful using a pre-treat, very high dpi photoshop images, and an underbase.
It takes diligence, experimentation, and patience, but with a little effort, digital printing can produce a very high quality result and it can be profitable.