It's been several years since I subscribed to the site (only did so I think twice or three times in order to save copies of as many pedigrees as I could); I wouldn't say it's a very impressive setup, certainly not considering the status 'Burke's Peerage' carries. I recall the vast majority of pedigrees were simply taken from the last volume in which a family appeared; there were many from BLG 1969.
There is now a 'new and revised families' section, which does update a number of peerage and baronetage families (e.g. Marquesses of Anglesey, Cave-Browne-Cave), but to my eye many of these 'new' families are not of any real interesting lineage or note; take the 'new family' of Arnhold Simoes, for example. Searching the surname brings up nothing much except reference to a Christiano Arnhold Simoes, who according to the Armorial Register is 'Earl and Lord of Aboyne'. This is clarified below, where it mentions his 'having acquired the baronial dignity of the Earldom and Lordship of Aboyne' (although 'Earl of Aboyne' is a courtesy title in the family of the Marquesses of Huntly?). He seems to be employed in some kind of financial capacity.
I am not currently subscribed to Burke's so obviously can't check the extent of the pedigrees, but, frankly, I'd be hard pressed to muster interest in the pedigree of a fellow who's just done quite well in business and then bought a baronial title. I for one am not interested in seeing pedigrees- of which there were a great many in Burke's most recently published gentry volumes- headed by the 'noteworthy' individual (I distinctly recall in the Welsh and Yorkshire volumes there were huge numbers of minor local officials and businessmen, not inherently uninteresting necessarily, but to my mind not really fitting in with what I would be looking for from Burke's), giving the scantest details as far back as their grandfather. They may technically be 'gentry' by virtue of the position they have attained, but I can't help but feel a separate volume for this category would be of more use).
There's also a 'featured families' section under 'genealogies', which has details of the sovereign families of Europe as well as some others, which are up-to-date and I should think are representative of the 'new and updated' families pedigrees in format and extent of content.