Octopus sashimi is sliced very thin. This makes it much easier to eat.
Before slicing, octopus is tenderized and then boiled. Poorly prepped octopus can be extremely chewy.
And if the chef cuts the tako too thick, it can be like eating rubber.
But well executed octopus sashimi (and sushi) is delicious. It has a mild flavor, but becomes sweeter as you chew. It’s also a fine match with sake.