Will Uruguay's marijuana legalization be a policy success?

Uruguay's House of Representatives have passed a bill to legalize marijuana.  It seems likely to become law.  It still has to pass through the Senate, but the Senate has an even greater left-wing majority than the House of Representatives, and the bill has the support of Uruguay's President Jose Mujica.  The BBC reports:  

The measure is backed by the government of President Jose Mujica, who says it will remove profits from drug dealers and divert users from harder drugs.

Under the bill, only the government would be allowed to sell marijuana.

The state would assume "the control and regulation of the importation, exportation, plantation, cultivation, the harvest, the production, the acquisition, the storage, the commercialisation and the distribution of cannabis and its by-products".

I once proposed legalizing and nationalizing the marijuana industry as a sort of radical centrist joke, a policy that would offend the conservatives (legalize drugs), the libertarians (let the government sell it), and the liberals (because government is so bad at running things).  Somehow Uruguay is on the verge of implementing this idea.  

It's worth noting that, unlike legalization efforts in the U.S., which have come about through voter referendums, the Uruguayan government seems to be running out ahead of its population: 

A survey carried out before the vote by polling organisation Cifra suggested 63% of Uruguayans opposed the bill.

I nevertheless support the measure and I'm fascinated to see what sort of effects the new law will have.  That being said, it will be difficult to measure the impacts of this bill.  Marijuana-related deaths could rise, but the measure would still be a success if a) alcohol-related deaths declined; or b) illicit trade is significantly reduced, thus taking money from drug traffickers or reducing drug-related violence and death.  These latter effects would be particularly difficult to measure, so there should be plenty to argue over for years to come.  Also, it is possible the government could use income from the new industry to good effect via social programs.