This sequence introduces Cruella, but it does a couple of other very interesting things as well with parallel behavior and with geography.
The preceding sequence uses the joke that owners resemble their dogs. The parallel between dogs and humans is taken further in this sequence, starting with shot 1 by Les Clark depicting the marriage of Roger and Anita while Pongo and Perdita take their vows in the foreground. The composition reinforces the fact that the dogs, not the humans, are the main characters.
Shot 2 establishes Roger in the attic and the dogs on the main floor. We also see the front door with its glass window. The geography of the house is very important to this sequence.
The sequence proper begins and ends with the two dogs animated by Ollie Johnston, creating both a symmetry and a reversal. In the opening shots, Pongo is nervous and Perdita calms him by licking his nose. In the final shots, it is Perdita who is nervous and Pongo calms her by licking her face. Their tongues have to substitute for hands as a way for the characters to touch and reassure each other.
It isn't just dog noses that come into play in this sequence. Noses are something of a motif. Milt Kahl has Roger place his finger on Anita's nose in shot 22 and Roger and Anita rub noses twice, in shots 22 and 94. Roger puts his fingers on Pongo's nose in shot 30 animated by Johnston. Anita holds her nose at Cruella's cigarette smoke in shot 42 by Kahl and Pongo snorts at the smoke in an uncredited shot between 43 and 46. In this sequence, noses (a logical choice in a film about dogs) are used to demonstrate both emotional closeness and distance between characters.
The geography of this sequence is split into three vertical levels. Roger is in the attic, Anita occupies the main floor and Pongo is close to the floor. The height of the camera specifies whose point of view we are getting at any given time. Roger is blasting away in the attic, trying to drive Cruella way with his noise. Anita is attempting to be polite, offering refreshments and distracting Cruella in shot 55 when it looks like Pongo might actually attack Cruella. Pongo is clearly unhappy, almost being trampled twice, subjected to acrid smoke, being approached against his will and hiding behind furniture. While Cruella is the centerpiece of this sequence, it economically communicates a range of responses to her by isolating the other characters in their separate spaces.
Roger's position off screen seems to be a cheat. In shot 16, we can see that Roger is farther back than the door to the attic. His piano seems to be against the back wall of the house. Yet when Cruella and Pongo look up to the attic, they look towards the front of the house. While it is technically wrong, it makes for clearer storytelling as both Pongo and Cruella are looking away from Anita in shots 59 and 63. There is no mistake who they are reacting to in these shots.
Cruella gets a great entrance. First, her car is heard offscreen. Then her car careens into view and parks in front of the house. Then her silhouette can be seen, framed twice within the door: once by the rectangular frame of the glass and once by the oval glass insert. When the door opens in shot 38, it literally explodes open, crushing Nanny against the wall. This, by the way, is the last we see of Nanny in the sequence. One can only assume she left to visit the nearest emergency room.
Cruella is flamboyant and aggressive, charging through the house in search of the unborn puppies. We know right away that she is selfish. She drives as if she owns the road and she visits as if she owns the house. She laughs at Anita's simple lifestyle and Roger's career, which only amplifies her rudeness.
Cruella is very much based on Tallulah Bankhead, the stage, screen and radio star who got her start in the 1920s and was famous for her way of flamboyant way of speaking and acting, which included chain smoking, a fondness for bourbon and conversations in the nude. She's perhaps best known today for her role in Hitchcock's Lifeboat (1944) and her standard greeting was "Hello Darling." Cruella's first words are "Anita darling" and her next line begins with "Miserable darling."
There's no question that Marc Davis's Cruella animation is memorable. She has the star part; the part that all the other characters revolve around and react to. Cruella's cigarette holder (didn't Marc Davis also use one?) provides lots of comic business, whether it's blowing smoke or putting out the cigarette in the pastry.
If this sequence has a weakness, it is Anita. Roger gets to do his sarcastic Cruella imitation once she leaves. Anita has nothing to do besides showing how demure she is relative to Cruella; she never gets more than slightly miffed through this sequence. Anita and Cruella are old school friends, but what is the attraction? Why, besides politeness, does Anita put up with Cruella? We never find out what keeps this unlikely pair in touch with each other and it's a missed opportunity. Unfortunately, there are no other scenes that give us insight into Anita either.