The scooter comparison is very true, even down to the material these things are made of (and the same rough edges here and there). Sure they don’t have Apple über attention to details, but they look neat nevertheless.
I also went down this route to secure my home network a bit more, and learn some things in the process. I picked almost the same hardware, but with wifi and a low power Braswell Celeron chip, since I am as concerned with performance as with power drain and heating (this thing is supposed to run at my place, I don’t want it to set fire to the cabinet where it sits). I once looked at Intel’s NUCs, but they are too expensive indeed, and the product configurations are impossible to figure out given their obnoxious names.
Mine will be replacing a much older Sheevaplug, with the added benefits of wifi, dual LAN, and much better performance. The Sheevaplug, although not under high loads tends to get quite warm in its plastic casing. These, whilst dissipating more watts (on paper at least), don’t come anywhere near the same temperature in normal operation.
Having a solid Linux distro to back these is a fundamental aspect to security. Constant updates are key, and being able to upgrade without spending a whole afternoon is important if you want to maintain a reasonable family life.