Walkers Marmite crisps were a birthday present from Dan. There's not much aroma to these chips. They smell like a basic, unflavored chip -- with maybe a hint of yeast -- only more so.
The taste is much stronger, but not instantly unpleasant. I've never had marmite, so I'm a bit of a loss to describe this flavor. There was an edge of nastiness at the back of my throat while I ate them, but it never quite coalesced into a bad taste.
I think if I hadn't heard that marmite is gross (such is what I've heard), I might have found these puzzling but fair. But marmite's reputation among its detractors (who -- around me, at least -- seem to number more than its fans) lent an air of menace to the experience.