I've got one and used it a few times, handled the 722.6 gearbox on my e class without much drama, it is a bit flimsy and you do have to man handle it a bit but there is no chance I'd of got the box back on without it.

I find usually you can't get the car high enough to get the box under on the jack then struggle like a bastard getting back onto the jack under the car

Done a zafira gsi with it too and was great, strap is prettty useless though use another strap and bin the one on it off if needs be.