Cheap
Having just ordered and paid for HSMs from a closed-source supplier and having to sign up to a licensing deal that is, quite frankly, daylight robbery I'm looking forward to getting one of these boards. The most important feature for me is that it is free of licence payments. The mainstream suppliers pull some clever strokes that require anyone who needs HSMs (that's anyone who needs to keep certificates and keys safe and to generate them safely and sign them) to buy multiple HSMs that have been deliberately crippled to prevent the user from re-deploying them elsewhere in the business.
The problem of course is that these devices have not been FIPS 140-2 certified so insurers and regulatory bodies are not going to accept that these devices are good enough to meet their requirements.