After long time waiting I have to say I'm content with the update.
I got so enthusiastic I even bought the Chambers dictionary to try out the new keyrepeat function, right after I found out about the new update. So one might say that Bookeen incites ebooks sales

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I went for the 1.5 version as I want to make use of the lookup function. The keyrepeat function sped up the lookup process. Btw. Mobipocket's selling Chambers at a discounted price. So you might want to check out the offer.
Folders are nice. Interface seems a lot snappier and more responsive. Dedicated lookup button would be nice, though.
As for the lookup latency, I noticed the search is faster with the dictionary on sdcard. I have only one book in the ebooks directory besides the dictionary and the search is nigh instantanous, so I guess the number of books in the directory is also a factor.
Thanks, Bookeen.