TL;DR: Works fine (see title).
The little old box
I bought my last desktop from VG Computing (now Linux Now) in Melbourne. It arrived without an operating system and was basically a Mini-ITX board in a Shuttle XH61 case, with selected add-ins. (Specs below).
I installed Debian stable and got years of quiet, cool performance. The Shuttle was especially welcome on my sometimes-crowded desk because it took up so little space.
The littler new box
I've replaced the Shuttle rig with an even smaller but more capable desktop, the Dell OptiPlex 9020 Micro (specs below). The 9020 Micro is no longer available in Australia from Dell, having been bumped by the similar 3040 Micro. However, I found a 9020 selling at a deep discount on eBay, and you can buy ex-lease units for around AUD$550 (I wrote this in June 2017).
See this article for performance tests on the 9020 Micro and a peek at its innards. It looks like Dell has aimed the Micro design at the corporate desktop market (as in "Buy 1000 units and get a discount!"), but to my way of thinking, the low power consumption and tiny footprint would make a Micro attractive to anyone but a gamer.
My Micro apparently came with "Win 8.1 Pro (Upgraded to Win 10 Pro)", but I can't confirm that because Windows didn't get a chance to run on the machine. I held F2 down during startup to access the BIOS menus and prioritised a USB stick loaded with Debian 9 netinstall. With Debian installed and claiming the whole of the SSD drive, I downloaded Xfce desktop and all my favourite programs, then transferred data files from the Shuttle.
The Micro runs more quietly than the Shuttle rig and barely gets warm. It doesn't have an optical disk drive (I use an external one when needed) but it has a decent built-in speaker, which the Shuttle rig lacked.
The Micro is teamed with a bracket-mounted monitor and an El Cheapo mouse. My keyboard's a bit fancier: a Perixx Periboard-407. I prefer the Periboard design because it allows my upper arm to stay vertical when mousing, not stretching off to one side as it does with a full-size keyboard.