The appearance of the 650 is more upscale than 600. Its dark gray and black keys give a certain standing in this remote control. Moreover the keys are placed in exactly the same way as the 600, I do not feel lost at all.
The Logitech Harmony 650 remote is easy to use, to plug the program on your computer and go to the site indicated by the instructions and follow the steps. Everything is programmable. What I love, simplicity, simply press "watch tv" and if you have programmed correctly, all devices are lit (in my case, the TV and the amp) simultaneously . To watch a movie, nothing more simple, select "watch a movie" and all devices come on!
The remote control has buttons on the DVD drive, the embedded numeric keypad and backlit keys.
In conclusion, the 650, for its higher price, brings us, compared to the 600 that a more classy aesthetics and a color screen. However I strongly advice because its value for money is unbeatable. In addition, this remote is on amazon much cheaper than on competing sites, so it's worth the blow to prefer the Logitech Harmony 600 remote. For just a few euros apart, you will have a nice product with less fragile appearance. However both are very sturdy.