ya these posts sum up my situation pretty well. used to have around 40-50 bbm contacts. slowly but surely they became dead ends due to android or iPhone switches.
made the switch myself a few months back, but still frequently swap out to my 9700. but with my BB friends able to download whatsapp, it's been easy to connect with the big 3 OSes.
another reason i use whatsapp, that the OP didn't mention, is that whatsapp is the only app to cover symbian OS. in the US, no one uses symbian, but my international friends use symbian, so i can now talk with them :)