My husband bought this belt for me as a present and I love it.  When they say "seatbelt" that's what it is.  The lock is just like a seatbelt lock (weight and all) and the cloth part that goes around your body is exactly the same as what you use in your car.  My only complaints:
- It's heavy.  I seriously could take this off and strap myself to the inside of the tardis during takeoff and be ok.
- After I adjusted the belt to fit me (I'm 5'4; 128 pounds) the white sign decoration that is similar to the one on the outside of the tardis is on the inside of the belt so its not visible which is disappointing.
- The plastic adjustment strap is a bit large and when you belt it through your pant loops it gets caughts so you have to wiggle it through each one.  It's not a quick pull through like a normal belt.

I've worn this out a couple of times and people always comment that they think its cool so overall I like it.  A bit of geek even if its hidden under my shirt.