Factorio couples a simple, rewarding core gameplay loop with enough activity variety, minimal downtime, and highly customizable difficulty to keep it a consistently high-quality experience. That's more than I can say for so many other titles which require a heavy time commitment for minimal "fun". Since its original beta release, it has transformed massively and now feels to be at the pinnacle of all possible executions on the core design concept. Extraordinary polish is evident in play, with the developers firmly committed to making it as broadly appealing as possible while never failing to make sure each individual aspect of it receives adequate attention.
The game is undeniably gritty and "grainy", and while it is an entirely valid stylistic choice (and executed masterfully), it can also come off as a little abrasive.

Problem is, this innovator of the genre suffers from a variety of flaws and kitchen sink mechanics which pull it all apart. We doubtlessly owe it some credit for initializing a lot of key ideas about what makes a good factory building game, but it doesn't do any one particular element of it with excellence, leading to a lukewarm experience. I've had much better times with other games that focused on the individual elements which make factorio good. This title is mainly valuable for historic merit.