Another big concern is that people who test at home won't have access to counseling about their results. It may be harder to find them appropriate care. It may also be more difficult to get them help for the emotional aspects of the diagnosis. There's also a worry that, unlike people who are tested in a clinic setting, home testers won't need to report their results. That makes it difficult to track new diagnoses and contributes further to problems channeling people into care.
Finally, there's a risk that people may decide to use rapid testing as an alternative to practicing safe sex. People who don't understand that these tests take up to several months to turn positive after infection may use the kit together with a casual partner, and then skip using condoms if both tests are negative -- without realizing that they are still at risk for not just HIV but other STDs. That type of behavior has been seen in pilot programs for at home HIV tests.
Still, on the whole I think that the ability to home test would be a useful addition to the HIV testing arsenal. However, I really hope that the tests come with well written, easy to understand educational information about what test results mean and what they don't... not to mention a good way to funnel anyone with a positive result into care.