Its true. I was there last week and made extensive use of the Subway. Every single station has checking, and as mentioned, its is extremely cursory and imo, a formality at best. On more than one occasion, I caught the screener napping in the back, and her assistant involved doing her nails. They didn't as much as look up and check who dropped and picked up their bag.

However, expect it to be more thorough around Tian'amen Square stations and entrance. Especially with October 1 around the corner.

Also, lax security at Beijing airport. Flying from PEK to Guilin, I had intended to move my pocket utility knife from my carry-on to my checked luggage. In the haste to get to the airport, I forgot. Of course, I didn't realize it until well into the flight that somehow I had managed to clear security without getting stopped.