What was the problem with the dictionary? I use iBooks' (English) dictionary extensively, and it's more detailed than the one that comes with the Kobo e-readers. Marvin uses the same one, I believe.
What would be an example of a free epub file that iBooks displays poorly? Not questioning the statement, just curious what the visual differences are (between Marvin, iBooks, Kobo) so that I have a better idea. My standards are probably pretty low.