ARS Technica reports DNA offers the capability for incredible storage density, one gram of DNA could potentially store the equivalent of one billion terabytes (one zettabyte)! Furthermore, it's also very resilient, earlier research suggests the technique may be economically viable to store data for 500 years or more.
One major roadblock is the difficulty of reading and writing DNA storage. This used to be an extremely expensive feat but the cost of genetic sequencing has dropped exponentially over the last couple of decades, meaning commercial use of synthetic DNA storage may soon become viable. Reading DNA material is done via genetic sequencing, the human genome project ran up costs of $3 billion between 1990 and 2003 but nowadays the same task can be done for just $1,000.
The big difficulty with DNA storage is reading and writing. The writing is done by Twist; the company can produce custom strings of DNA using a machine it constructed. The company's main customers are research labs that insert custom genetic material into microbes to produce organisms that can perform useful chemical processes, such as producing desirable nutrients. Using DNA for data storage is a new field for the company. A custom DNA sequence costs about 10 cents per base, with Twist hoping to get that cost down to 2 cents.