I have one and I can see the pros and cons. It's very well made, great to rest on and has useful storage.
But it does impede gear change a tad (if I was racing I wouldn't want it!) and it looks a little more cluttered in the car with it.
On balance I'd rather have it than not. If I was fitting one now I would have found a way of making the install removable as I think there might be damage to the trim where the glue is attached.
