i have a small list of needs when i look for an ereader
1) how well it handles pdfs. text only pdfs are simple but some of the rpg manuals that i have are just jpegs inside a pdf file. how the ereader handles these 70mb+ files is paramount as to wether it is useable to me. the limited processor and memory means that none of the ereaders i have tried does these satisfactorily. to date i have tried nokia 770, nokia 810. sony 500, 505, 705. cooler and an olpc. the olpc is closest but the speed and controls are just not there. will probably need a faster processor and a touchscreen to be useable.
2) battery life and charging. the longer the battery life the more likely i am to carry it. also i don't want to have to carry another power brick so the ability to charge of a _standard_ usb cable is important.
3) screen. bw screens are great. please don't feel that you have to include a colour screen just to compete with a competitor. i want battery life and to be able to read outdoors in sunlight. colour screens that i have used to date impact greatly on these 2 abilities.
4) search. i'm constantly astonished by how many of the current ereaders don't have a search facility or a good search facility. it's all well and good to read a book from start to finish but i like to have a stack of books on my ereaders and be able to search for a phrase or a piece of info in the reference books i carry.