I've been interested in eBooks for quite a while now, but the problems I have with all of them are not the small controls, or the lack of natural page flip options (though the idea here is rather cool).
My biggest problems with all current eBook readers is the very limited (and usually highly proprietary) formats that they support, and when they do support other formats the lack of efficiency in way they deal with it. For example the Sony eBook reader will read PDF's, but the further you go into a PDF the slower the page flips get. The same problem is not evident, of course!, when using the Sony default (and highly DRM'ed) format. Also the eInk technology is still rather slow in the page updates... Have not used a Kindle yet, so cannot comment on how it behaves or the efficiency of their alternate format supports.
So far the best reader I have found are the Fujitsu P1510/1610/1620 series of small form factor tablets. Using a standard OS on it, I can load any eBook reader software I want, and still be able to use it as a travelling computer when I need it. Of course the weight is much heavier then the "real" eBook readers, but at least I'm not restricted to their formats.