Depends on who is running the network and who owns the exit nodes. I'd really not consider it to be particularly secure. It's probably alright to use if your goal is to keep corporate entities from building a profile on you. But that's kind of pointless though if you are doing any sort of online shopping or whatever anyway since you'll have accounts and they'll know it is you anyway.

I've messed around with it a bit but there really isn't much point in using it I think. You are better off just getting a regular VPN for most circumstances.

Ordering drugs online just sounds retarded to me in general. Like even if your connection is totally secure you have no idea if the seller is compromised or not. Plus with TOR anyway nobody knows who is running the system or the exit nodes so while your particular online session in and of itself is unlikely to be tracked by any random person or company for all you know it's the CIA that owns the exit nodes anyway and they can figure shit out with their resources.

I think the main use argument for TOR is to allow people in oppressive foreign regimes to send online messages critical of their governments without fear of reprisals since it will be extremely difficult to track who is saying what. The easy solution for oppressive foreign regimes to fix this problem though is to simply ban Tor outright and arrest people who use it, so it is of very limited value.