i read a lot of reviews and info about the LB maps and picked them up for my trip to baja earlier this year.
needless to say, it couldn't even accurately get us through Mexicali without getting lost. beyond the actual cities themselves, i found a map to be easier for planning as the coordinates were off enough on the GPS that it was always "recalculating".
i love my GPS though and use it religiously state side. given the fact that the maps are $100 and non-refundable, i would strongly advise investing in some good maps and tips available from people's posts on bajanomad.com - the maps can come from AAA or a more durable version at the bookstore.
YMMV.