I like the aluminium case but I have the slide under the TV and if it was using a good plastic case (mine is black) I would not be able to tell the difference. I guess plastic would make the slide cheaper and more competitive with other solutions For what saw while waiting for our units, the aluminium case was the biggest headache and reason from most of the delays.
When I ordered the Slide it was because I thought the Ambilight system was going to be produced but it seems on hold forever .This was (for me) a clear differentiation for the system.
For feature reviews of the HW, I would add IRBlaster (short and long) for AV and home automation and a presence detector (similar to NEST). With this you could make the Slice to do a lot of fancy tricks once we have the CPU power of CM2: Control HUE, control heating/air conditioning, control home theater,...