It's great at building tension but the actual action is pretty underwhelming, as you say.
But it's quirky, because there are some great action shots too. E.g. Jackson Lamb. But those tend to be tighter, usually interior shots.
So maybe they should avoid the grand exterior action sequences.
At which point it does that British television thing where action just isn't.
But given there isn't a ton of actual action in it, the bulk of the show holds up.