I love how I always get exited about getting the newly updated books, the bad thing is I very often get disappointed by the lonely planet. Updating from your desk is not very useful.
This is second time round travelling in Argentina, and this time I spend 7 weeks in BA and all the way down south.
I went to Argentina 4 years ago for the first time, and I have to say not much updating has been done since that time.
Bus prices are still same as at that time, reality is a bus journey of around 20hours its not 200 pesos any more its 700 pesos, just over £100! Same thing with accommodation prices, and with the places that no longer exist.
I travel very often and found this to be the case with few of the LP books. I think they have the name now and sales are up, no matter how accurate the information is.
Enjoy Argentina, it is an amazing place, but don't count on the book every time.
G