You also realize that "user amounts" of hard drugs has been a misdemeanor for several years, right? It can be enhanced if the person has prior felonies or multiple misdemeanor drug convictions, but it takes quite a bit to get a new felony possession of a controlled substance conviction.
And Oregon is far from alone in that aspect. Utah has almost the exact same laws on their books. It's part of the Justice Reinvestment Investment initiative (JRI) from several years ago. Unless a person has prior felonies, it takes getting caught (and convicted) at least four times with user amounts before it becomes a felony. I'll bet the majority of states have similar laws if they're taking JRI grant money.
Oregon took it a step further and went from a misdemeanor to an infraction. The burglaries, robberies, thefts, assaults, sex crimes, etc. that go hand in hand with drug use are still felonies and is how any DA who doesn't agree with the "new law" is going to hammer people.
