I used the updated Bicimapas (2013 v. 8.0) on a recent rip to northern and central Mexico. The routing and routability are quite good and the newly added topographical information is very nice. The POIs, as mentioned by someone else, are very scarce, especially for hotels, where you need them most. For some reason, while you are in a fairly large city, like Zacatecas, the POIs that show up are for hotels a thousand km away.
The latest version of Bicimapas combines Mexico and Central America (and I thought Venezuela, but I can't find it on the maps), which is nice because the two of them separately were quite pricy. The owner of Bicimapas is quite responsive by e-mail or phone (located in Mexico) and once you have the proper code for a properly owned routable GPS, the download and installation are seamless.