I had the chance to have a play with the Lexus Remote Touch system in a RX450h last week. The vehicle was stationary at the time so caveats must be applied with respect to the system's performance under driving conditions; however I can report the following:
On the 'Home' screen, there are five icons in a horizontal line, which are selected with a pointer (much like a standard computer mouse) operated by the Remote Touch controller. The pointer 'snaps' between the icons with a definitive haptic 'click' from the controller which is very effective. However, the pointer is not constrained from moving vertically, which means it can stray into the 'free' space above and below the icons where its motion is unconstrained. This then requires visual attention to get the pointer back on track.
A brief test of the navigation system highlighted a surprising number of button presses and menu levels required to successfully input a UK postcode. The postcode option appears on the second page of the navigation menu, requiring users to move the pointer to a 'next' button, then select this option. Input is via soft QWERTY keyboard, albeit one with no numeric characters - to input numbers a button is clicked which brings up a dialogue offering the option of either numeric or symbol characters. This process has to be repeated to revert to alphabetic characters. Given that postcode entry is, in my personal experience, the default means of destination entry, the process seemed unnecessarily long-winded and complex.
One of the benefits of a touchscreen interface is that the user can directly access a specific function on the screen regardess of where it lies - the 'finding' is done visually. It would seem that Lexus have retained this philosophy for their interface software, while replacing the hardware with a system that requires the 'finding' to be done both visually and manually.
In short then: An interesting development in interface hardware, hampered by frustrating software. Perhaps we will see this system mature over future model iterations.