The Sony Reader gets one huge strike right off the bat from me… it requires a Computer running Windows OS (not Macintosh compatible). Probably not a problem for you (and I have XP Pro installed on my dual-boot Intel-based iMac), but that's always a stopper.
I do like the smaller size & lighter weight of the Sony, and truthfully the only other competitor is the Amazon Kindle (forget the eBookwise-1150 and the iRex Tech iLiad). However, the dark horse in this competition is the iPhone, which may yet become a serious competitor to both the Sony & Amazon product.
If I had to choose one today, however, I would go with Amazon's Kindle. More expensive, larger, and heavier, but with capabilities and selection that the Sony cannot match. A biggie... no need to go through a computer. The Kindle has 3G access so you can browse and download books, magazines, journals, newspapers and even blogs while riding the bus, at the beach, or on vacation. The users I've spoken with pretty much agree that it is the best of the bunch (though the weight/size is still a concern).
However, I'm still inclined to wait and see what may develop with the iPhone... it offers similar capabilities to the Kindle in a lighter/smaller package than the Sony and if Apple can develop a similar selection & ease-of-access/purchase that Amazon has implemented (and past history with music & videos would suggest they can), then the iPhone may become the de facto victor (despite it's smaller screen).
Just a few musings from an admitted Apple fan-boy. :cigar:
not an ebook but currently using an asus eeepc which is a brilliant little tool and very compact. probably some free sofware about to make it more ebook like but would hve all the usual laptop advantages