And no, there was no 20 minutes of "silently wandering around the streets." The characters had a destination in mind, and they were going there. On foot. You might as well accuse a mailman of "wandering" because he's on foot and not speaking to anyone for the majority of his route.
Having a location in mind doesn't matter. Its the actual journey that was pointless and wandering. In any other episode, traveling from the TARDIS to a museum, and then from the museum to a cafe, would probably be less than a minute of screen time (if nothing happened while they were walking). In this, they stuck long, pointless,
uneventful shots of them walking in Paris.
That was the problem, it was pointless long shots of walking where the shots themselves didn't have a point in the story. The locations they were traveling to did, but the actual walking itself was pointlessly drawn out. They weren't attacked, or finding plot relevant stuff, or anything. They were just going from point A to point B in the longest way they could get away with, and nothing of note happened during the trips.
Yeah, I can see it now:
Producer/Director/Writer: "We're spending a lot of money here, so let's just have Tom and Lalla wander around for no reason, and figure out a story later."
Tom Baker & Lalla Ward: "Cool!" (or whatever the appropriate British expression is)
That's how you see this story, right?
Of course they figured out a story first, they just built it either knowing they could pad at least one episode out with monotonous location shooting that did nothing but fill time, or they realized while filming that extra walking scenes was needed to fill time or something. Either way, it worked out to them having less story than most episodes of Doctor Who, and replacing the minutes of story with walking.
Oh. Come. On. If you didn't care about the location, you wouldn't have typed the phrase "wandering aimlessly/randomly/pointlessly around Paris" enough times to make me sick from alcohol poisoning if I were to make a drinking game of it.
I don't care about the location. If this had been set in London, I'd complain that they spent 20 minutes wandering around London. It wasn't the city, it was showing a bunch of traveling footage that gave nothing to the story, and just filled air time. It doesn't matter what city it was set in, except that they probably wouldn't have filmed it this way if they were in London instead of Paris.