The registry site states that ".BI Registry has a rather liberal policy about domain names as soon as the domain name is in relation with the business name or one of its marks. The general principle is that a domain must reflect the truth." Registrations are open to anybody worldwide, but are not supposed to be registered or used for misleading purposes, though apparently no pre-screening is done to ensure this. The site also states that "We strongly discourage the use of suffixes of our country for misleading people. We remind that .bi stands for Republic of Burundi and for nothing else." This is apparently intended to discourage the "repurposing" of .bi as has been done with other ccTLDs (such as .tv for "television" and .la for Los Angeles), or the use in " domain hacks" where the TLD becomes part of a word or phrase (as in del.icio.us). Use of "bi" in the sense of bisexuality is likely the sort of thing they are aiming to prevent, though it is unclear whether there have been any actual uses of the ccTLD in this manner. It is used by the Israeli company Vision.bi, which develops Business Intelligence software.
There does not seem to be very much use at all, either within or outside Burundi, despite the liberal registration policy. The nation's political and economic situation may at least in part account for the relatively low number of registered domains; Burundi is among the most impoverished nations on Earth.
.bi is one of the minority of ccTLDs which has signed a Memorandum of Understanding (MoU) with ICANN, something ICANN has attempted with limited success to get all ccTLD registries to do. The .bi registration agreement also subjects registrants to the UDRP dispute policy, but they do not appear to have contracted with WIPO to place disputes in this ccTLD under their panels' jurisdiction, and there is no indication in the registry site of any other adjudication body authorized to hear such disputes.