They're great when they're working. You never have to bother checking your tyre pressures unless you have a puncture - and that (believe it or not) is one of their original downfalls, because the metal caps used to corrode onto the valve stems. Often, you couldn't get the cap off without destroying the valve :crazy:
Lots of people have had problems with them, not least of which is the fact that if one fails, you have to pay Renault to install a new one. I'm sure they could have made the car intelligent enough to 'learn' a single new sensor at a time, but where's the profit in that?
Retro-fitting the Renault system is probably going to be tricky. Depending on the model too, it might not even give you actual tyre pressures - just a low pressure warning.
If you really want this, then I'd be more inclined to consider an after-fit monitoring system. I know that Tyron do one for starters, and while it ain't cheap, it may well end up cheaper than trying to retro-fit the Renault ones. Besides, it'll hopefully be more reliable and should be transferrable to your future cars. Tyron also do various run-flat tyre systems - I don't know if these have to be fitted to use their pressure system, or whether it can run independently.