In season one I really enjoyed it, season 2 was pretty great as well but also it was basically just season 1 all over again. I think if they are smart they will make season 4 the last one because the viewership is dropping.
I will still look forward to season 4 for sure, but they better mix it up a bit before they lose me and a lot of other viewers because unless something big happens with the Mexico side of things, they just seem to be running in circles. That's just my opinion though :)