Log house in solid wood or post-and-beam construction - experiences?

You can't really say that in general.
In our demolition, a lot of wood was untreated.
Allegedly, this is not necessary if it was cut at a certain moon phase, during a specific season. (say the old woodworms from the village and my grandpa also swore by it - and the condition of the barn seemed to prove him right)
That might still work if you’re cutting trees in your own forest, but it doesn’t work industrially and affordably. If insulation and stuff gets involved, it’s over.
Weak points in the old half-timbered construction were always where modern building materials like Styrofoam wallpaper, PVC flooring, etc. were used.

...Unfortunately, you have no idea, but that’s not a problem unless you are an engineer.

Cheap response from a seller afraid for his arguments!
10% higher construction cost for 50% lower heating costs sounds like spending more than €25,000 and saving €30 per month in expenses.
Don’t tell me about spending and saving! I’ve calculated it and won’t be lulled by sales talk!

...Weak points in the old timber framing were always where modern building materials like styrofoam wallpaper, PVC flooring, etc. were used.

The timber frame was not designed for today’s ultra-tight construction methods. In houses, air was allowed to circulate and usually only one room, mostly the kitchen, was heated.
That was not a problem back then; the concept for new houses (all rooms heated except one) would be a death sentence for today’s new builds.

On the topic with a request for completion:

Advantages of solid wood walls:
- Moisture regulating
- Appearance (for fans of this construction method)

Disadvantages:
- Expensive
- Sanitary and electrical installations must be fully discussed and determined already in the planning phase

Advantage of timber frame construction:
- Short assembly time thanks to prefabricated component groups

Disadvantages:
- Sanitary and electrical installations must be fully discussed and determined already in the planning phase

What do you understand by solid wood wall? Wood without anything or also the solid wood walls (cross-laminated, nailed, with exterior plaster, insulation, and partially clad on the inside.

What do you understand by solid wood wall?

Solid wood refers to wood sawn as it grew; in contrast to solid timber, which only means that there is no engineered material between the visible layers: laminated veneer lumber is also solid timber, but not solid wood. Solid wood is less "eco" because it produces more offcuts/waste, which usually can only be machined further. I consider laminated veneer lumber relatively more sensible, but ultimately both primarily target the audience of "eco-bio posh salon communists" – that is, the same people who refuel their cars with nuclear power, whose floor systems consist of tens of thousands of series-connected phone batteries.

Then solid wood is missing in the lineup

By the way, I drive a gasoline car and am not eco-friendly

You also know what I think of the eco-sales talk.

I am satisfied with my solid wood house without exposed timber