Does this mount let you mount the one x in landscape? or just portrait?
Landscape or portrait. It swivels 360 degrees, so you can easily orient your phone however you like.
I've had this mount for 5 or 6 months, and it works great. In particular, the sides do not block the MicroUSB port or volume rocker on the One X. So you can easily have the phone in landscape for Navigation, and charge at the same time.
The mount is well thought out, and well made. It installs securely into the CD slot, and holds the phone securely. Like others, I wished the ball joint had a little more freedom to tilt in all directions. But this is a minor quibble, and this mount is a great solution for many people.
A couple things to consider before you buy, depending on the location of your CD player, the position may not be ideal. If you intend on using your phone for Navigation, the CD slot location may be too low. Also, you should consider if any important dashboard controls or displays will be blocked. These are usually not considerations for suction cup mounts. But for my car, the CD slot mount is an almost ideal location. Its near the top of the dashboard, so the screen can be easily seen for Navigation. And it blocks a minimal amount of the air vents and hazard light button (still sufficiently accessible).
Another thing to keep in mind, as indicated by the manufacturer, the system of installation may cause the dust guard on your CD player to become deformed. The spreaders on this mount actually tore the fabric dust guard on my CD player. But the mount has hardly ever left the CD slot since I bought it, and its unlikely to come out much. So I could care less.
The best thing about having this mount, my friends keep getting in my car and saying "Whoa, is that phone holder
in your CD slot???" lol