John's piano can't really be called "utterly unremarkable." This is because it's not any old saloon bar or knees-up "Joanna", but a Steinway Model Z, made in Hamburg (most Steinways are made in Long Island City, Queens, New York). Model Zs have never been cheap to buy. I think what Ed means is that this particular piano, with its mechanism housed in a bland, functional 60s-style casing looks "utterly unremarkable", while, of course being special in every other way. This includes the way it plays, its smooth, mellow tone and its big Steinway sound that, while no match for the same company's magnificent Model D Concert Grands, is something really quite special.
While certainly not an "everyday design" in terms of cost, performance, craftsmanship and sheer overall quality, the Steinway Z is a reminder that some of the very best machines and artefacts around us can seem quite ordinary, almost banal, if only looked at rather than used. And, it's true that John Lennon's Steinway Model Z does look very much like the sort of piano you might find in a school hall or the living room a of music teachers struggling by on a music teachers' salary while dreaming, perhaps, of sitting at the keyboard of a Steinway Model D.
Lennon's piano, then, is the very opposite of either "bling" or "iconic" design - fashionable today - both concerned, unashamedly with, first and foremost, the ways thing look. And provoke, gleam and generally grab the attention even of those trying hard not to look their way.
Thanks to Gabi for the link.