I love my kindle 4 nt.
The kindle nt is perfect to read prc, mobi or azw files.
epub to mobi conversion is very good and very easy with Calibre.
Reading is much less tiring than through a computer screen.
But i really would like a better support to pdf files.
Unfortunately, .pdf to .mobi still sucks.
90% of what i read are pdf files and because of that i am thinking buy a ipad.
Good Luck.