I had one , was quite pleasant. Not like mb leather smell at all. Was a musty oldy worldy smell from it, but definitely leather and quite nice smelling
Imagine getting into a 1980's jag or bentley or similar. Smells like that.
Lasted for quite a while , i got the one that straps under the seat.
Now have a S212 350 PETROL! . Did have 1992 W124 300E Ford Escort 1300E(now sold!)
I gave used the air fresheners.I hung it on the rear grab handle and the smell of leather permiates the cabin when opening the door,very nice and worth the £3.95 for two.
They do smell quite strongly, but it's very pleasant. It might be advisable to simply open the packaging and leave it under a seat while you decide whether or not you like it.
As fuzzer said, it's more like an old-school leather smell rather than that of a new MB interior.
Why not just get Gliptone G11 conditioner, that brings back the smell of leather, + you'll be conditioning your interior as well, doesnt take long, and as you dont use much, the bottle will last several uses, and it only cost £7 odd.