Radio Text has been around for a while - I had a Kenwood HU in 2000 that had it (but it would only work if you were within about 10 miles from the transmitter) and then a 2001 Alpine HU where it worked perfectly.
Not missing much IMO, it just scrolls a line of text that says something like "BBC Radio four, question time, John Humphreys asks questions, contact
qtime@bbc.co.uk". Would look pretty on the satnav screen, I agree.
Don't confuse this in the setup options with the normal RDS text, which is just the station ident (BBC R4).