As for your second question...'is it worth it?'...thats a tough one to answer. If your a responsible adult to begin with the odds of you actually getting in trouble for using marijuana are pretty slim but if you did ever get charged you could receive a misdemeanor or in some cases a felony and you would be burdened with not only a criminal record but also fines and court fees to go along with possible jail time....so in a way its a great insurance. If you have a hard time getting your meds right now or plan to grow it would help you the most, for example: instead of calling your friends friend to get your weed only to have it delivered 3 hours late then you might appreciate the ability to drive up to the club or dispensary spontaneously at 10am if you so desire and get your hookup then it can be a nice convenience - or you can grow for yourself at home and never have to go anywhere with marijuana and have a license to do so
The only scenarios that I would say 'not worth it' include:
1) If you plan not to follow the rules and regulations set by the act, you could get in a lot more trouble then if you would of been illegal because breaking the rules is a felony in itself. If you plan to grow or posses more then your allowed then you might as well not get a card in the first place as you would be better off without one.
2) If your marijuana use is private enough that you would likely never get caught and self sustaining in that you don't need better resources, example: you use a very small ammount and are so cautious that you never leave your home with it and you literally never drive with it in your possession, you never get in trouble with the law and your not growing, Id say its not worth it if you are in this type of situation it would be kind of a waste of money - however, even if this is your situation some sort of emergency could happen or really anything and the next thing you know your spending 30 days in jail for 3 joints.....you never know shit happens...weigh the risk...evaluate your options here.