One of the things that I find very compelling about the Flexchannels is when you consider their use in non-digital applications. Each bit of the 8-bit input has logic threshold than can be varied between +/-40V. I have worked with many customers where this is a very valuable feature. Consider avionics applications where there are dozens of electro-mechanical actuators, sensors, etc. that needed monitoring, or RADAR applications where there are many discrete signals (gating signals, power for various modules, RF switches, etc.) present in a system. These flex channels give the engineer the ability to get a system level view of their analog signals, logic command and control, as well as multiple supply, sensor, and other system level signals. Features like this are a huge development investment, and certainly are not undertaken in a vacuum - they're result of years of customer application focus and feedback.
One of the nicest features of this scope, that unfortunately doesn't show up well in video, is the *high-resolution* display. Not only is the display big, it's 1920x1080 resolution is better than my laptop! This gives you really nice, non-intrusive vertical and horizontal axis labels, crisp and informative dialogs and menus, and of course, high-res waveform quality.
Like Joel and Brian have stated, it's hard not to be a bit biased since I work for Tektronix. However, I spent 25 years as an engineer, as a test equipment customer/user prior to joining Tek - and this is certainly one of the nicest scope developments that I can remember in my long career.