I'm in the same camp as XBEHERE. It's so much easier to just bring ONE thing with you to the meeting...no Bible, no song book, no WT, no KM, no Jeremiah book, etc., etc...
EDIT: To Gorby's question as to why the GB even has to be involved in "allowing" tablets to be used is a bigger question for me. After all, using tablets in worship was actively encouraged under the Mosaic Law...even if Moses did manage to break the first couple he got.
Some might think that type of rule making is a bit Pharisaical.