Don't get me started (I may get myself banned if I speak my mind). IMHO, there are many improvements to be made to the Lexus system.
The remote touch (whether it's the track pad or the mouse) requires the driver to physically take their eyes off the road and look / hunt for the "cursor" before selecting the option. This takes time. At least with the older touch screen, the mind / eye will focus on what it wants and your finger will basically go to it (think about you walking up to a computer and grabbing the mouse - it'll take you a second or two to figure out where you're at and then "guide" the cursor to your desired option vs the iPad where your eyes / finger will be in sync). This point has been proven by many independent UI / UX designing firms.
Next would be screen layout. The great thing about MMI and other more "Germanic" systems is that their screens are somewhat consistent. Using the MMI as an example, that same turning knob / multi-directional toggle can basically perform all tasks by doing the same thing (i.e. turn left, right, push up, down, etc.) The screens (HVAC, media, navigation entry) basically work off of that premise so it's much easier to use and to be honest, much safer when you're driving.
Navigation - it sucks that there is no good way to scroll around on the map. You have to go to the edge of the screen and tap, tap, tap. Half the time, the cursor "pops" onto a command instead of staying on the map for me to tap / move the view. Again, other systems out there really excel in ease of use in this area.
Voice recognition - even with the expanded command set, it doesn't understand me half the time. Maybe it's my voice. But then again, Siri gets it spot on almost every time. So it's crazy to think that a $250 iPhone has more processing power than a $50k car (granted the DENSO supplied head unit is not $50k but a fraction of that).
There is no perfect system. I know that. All I ask is give me the option to use "traditional" dials and knobs. Do not force me to use the screen. For example, did you know that there is no fan / blower control in the LFA? Well, it's accessible via the climate control screen which requires 1 click of the MENU button, a move of the remote touch joystick until it highlights Climate, a press of the side button to enter the Climate screen, a move of the remote touch joystick to hover over the fan speed selection, and a final press of the side button to lower the fan speed. Guess what, if there was a button for fan up/down - it would be 1 button push. Yes, yes, yes. The LFA is a poor example because it was not designed with those things in mind. But it's just an example of trying to stuff everything inside a screen.