Unless you have 2ft thick stone walls, double course brickwork on every single wall, foil lined plasterboard/foil lined underfloor insulation on laminate or the kind of home that has a wing for the servants, getting decent WiFi is usually reasonably simple. Run a cable from the router to a central location on the top floor and drop it through the ceiling, connect a PoE injector at a convenient point (unless you have a suitable PoE switch) and mount an AP on the ceiling connected to your cable. You will now usually have decent WiFi on the top floor and the floor immediately below it, I even have decent coverage on the ground floor, though 5Ghz speeds aren’t so great.
If you prefer not to have an AP mounted where it can be seen, they survive quite well in roof spaces which can make installs quick/easy. Larger homes or homes with extensions may need additional AP’s, for example my parents bungalow has a 2ft stone wall in the middle of it due to being extended, understandably WiFi is non existent on the other side of that, another family property is quite large/old and every single wall is twin course brickwork, and not your modern aerated stuff, this is solid. The general rule is, if you have to go through more than one wall, you probably need another AP to extend coverage and if that wall is a solid brick wall, you may need another AP anyway for decent speeds.
As to mesh, it’s a nice idea, but unless you have a wired backhaul or live in a bed sit, it’s a compromised technology, it’s worse still if it shares the backhaul radio’s with clients as the cheap offerings often do. If you want decent mesh with a wired backhaul, AP’s probably make more sense anyway. As to why reviews vary, you have to remember that people expect mesh is some sort of magic that defies the physics of an environment where they already had issues, they usually don’t understand how it works or really want to, they just know if it’s faster or not according to the sync speed and perhaps the Speedtest app.
