However I would define worst of all cases is for the manufacturer to include a functional SD card slot and then virtually cripple it in the software. Can't get more user hostile than that.
Agreed. Fortunately Archos do not seem to have gone this route.
I have used the microSD card slot for (among other things) music, videos, pictures, ebooks, html files, and PDFs. The built-in apps have no trouble playing files from there, and the standard file manager can move stuff to and from there. Admittedly, many apps don't allow you to tell them to store data there, but a lot seem to cope if you move the files there 'by hand'. When on holiday I no longer need to take my laptop to be able to view and archive photos off my camera: the G9 does all that for me, as well as acting as my web browser, mail manager, book reader, music player and video player. Although the screen quality and build quality do not give the G9 the pizzazz of some other tablets, the price, form factor and connectivity (OTG-capable micro-USB socket, full-sized USB socket, wan, bluetooth, standard headphone jack, hdmi, a-GPS) mean it ticks the boxes I need -though there obviously room for improvement (such as a microphone socket, support for more bluetooth protocols, and the ability to work better with third-party chargers). Other people have different priorities, and (judging by other posts on this forum) later editions of the device seem to suffer more from build problems or compatibility issues, so my opinion is a personal one, based on my experience of my tablet, and my pattern of use.