Depends on what is inside, intel N100 or better CPUS are considered really good in general. There are some bad CPUs in mini-PCs though. Make sure the hardware has drivers for your choosen OS, not everything supports linux [well] even today. And every once in a while someone makes a PC with bad design and so it doesn't work well for technical reasons.

There are a lot of small PCs that are low power that will work well. I haven't used GMKTech's, and one look at their website says I won't try to navigate that mess. (why does everyone need a subscribe to our newsletter popup blocking my ability to see anything - I avoid anyone who abuses me like that)