I saw lots of Uruguyans upset on Reddit, and I have some Uruguyan roommates that explained to me why they hate Mujica.
A couple recurring points:
1. Education worsened. 2. Crime skyrocketed, one of my roommates was a cop in Uruguay and said when he was a cop there was about 350 arrests per year, now there is that number in one month and only in the capital, and for more violent crimes, like murder, where the most serious crime he usually arrested someone was stealing without using force. 3. Although the president is populist and socialist, somehow people now are starving, my roommates are here in Brazil to earn money to ship to their families, and they said this was not necessary before Mujica, one claims that the government took 150000 USD that his mother left in a savings account. 4. Mujica openly bribed voters. Several expat Uruguyans repeated the story that Mujica paid airfare to anyone willing to go back to Uruguay during elections and vote for him. 5. Mujica is fake poor. Although he gives away his salary, the population believes he gets a cut from Brazilian and Argentinean gold laundered there. 6. Marijuana was made legal only to increase government revenue, not in form.of taxes, but by having a law mandated monopoly. There are lots of other complaints, these are the common ones.