I don't like the wasted space either at the top or the bottom. There's no reason you need to take up space with the book title at the top. And the bottom bar space is at least 2.5x the height it needs to be.
Here's a comparison showing the Sony bottom bar next to the Kobo Glo. That's the height I'd like to see on the Kobo, there's no reason to need anything larger than that. Takes up minimal space yet plenty of room to show information.
And the ideal choice would be to have both settings be an option, where you can turn them off completely if you choose, especially since I think they'll never reduce the size of the bars.