As far as I know, the only thing that changed recently is that hallucinogenic mushrooms became illegal in November. Cannabis in all its forms (marijuana, hashish, hash oil) is legal for personal use, though technically illegal to sell. It is widely tolerated, however, as long as the practice is not abused.
It should go without saying that you must be a conscientious tourist. Wherever you travel outside your home country, you are essentially an ambassador for your country and your actions must reflect that. Avoid being obvious, belligerent or publicly altered (no matter the source), don't try to re-sell weed and obviously don't try to take any out of the country with you. Read the second link for more practical information.
Have fun! And don't forget to stroll the red light district. Absolutely fascinating.