To all those who are pro-marijuana, but think I-502 is a mistake:
Note: I wrote the Local Government Fiscal Note for this bill. 
1) Regarding the per se 5 nanogram limit on DUI: 
this law clarifies what can be tested in one's blood. Currently THC byproducts can be tested for. Byproducts do remain in the blood for a long time, especially for heavy users. Under I-502 only active THC will be legal to use in determining a DUI. Studies show that active THC stays in the system only a few hours - even in the heaviest users. YES, it will be easier to get a DUI under this law for Marijuana. Currently the jury has to agree that you were intoxicated. However, this per se limit WILL BE challenged in the courts if it doesn't get modified or removed in the legislature first. Also, the officer will have to have probable cause and take you to a certified lab, all of which takes time; officers may not always want to do this. Does the 5 ng limit make sense? i don't think so. I think the courts should have to prove intoxication. I hope to see the per se limit go away. I-502 revenues will fund research, so hopefully we will know more about impairment from THC, especially since there is so little research on it (because it is illegal...)
2) Regarding dispensaries: they will still exist. This law has no effect on medical marijuana.
3) The bill does not set a limit on how much THC is in the product. Marijuana will be classified into different grades.
4) the bill REQUIRES that distribution of legal marijuana will out-compete the black market - yes there will be hefty taxes, but prices will be about the same as they are now - if they are too high and they can't compete with the black market, the Liquor Control Board would be breaking the law.
5) This will save a lot of people from going through the hell of the legal system and incarceration, and will save us millions, if not hundreds of millions of dollars (not to mention the revenues).

Do I think this is full legalization? No. Is it perfect? No. But it is much easier to CHANGE a bill than it is to pass a new one.