In critiquing the show I would characterize it as a Broadway style song and dance revue. The two stars were Katherine and professional ballerina Darcy Bussell. It was pretty easy to pick out who the professional dancer was and who the professional singer was. It was actually quite enjoyable with excellent performances by both stars. The ladies did covers of famous numbers from stage and screen. Katherine covered material from Barbra Streisand, Edith Piaf, Marylin Monroe, Natalie Wood, etc.
Most of the dancing that Katherine did in the show would be characterized as stage movement as opposed to hard core dancing by anyone familiar with Broadway style theater. The most extensive dance that was done was tap dancing. Here is a list of the dance routines Katherine participated in:
La Vie En Rose - This routine was done while she was singing the song made famous by Edith Piaf. I would characterize this as light dance with some members of the dance chorus whom she interacted with during the singing. She did a few turns in waltz dance hold during the routine.
Let Me Entertain You - If any of you remember the finale from the Broadway show "Gypsy" this was a knock off of that routine. It was stage movement not hard core dance.
Diamonds are a Girl's Best Friend - This is a knock off of the famous movie scene that Marilyn Monroe and Jane Russel did. Katherine sang and played the part of Marilyn. Once again, stage movement not hard core dance.
Habanera - Katherine sang this famous aria from Carmen. Part of the choreography involved some light flamenco kicks and stomps along with interaction with the male chorus dancers.
Everything old is New Again - This was the final piece in the show and the one in which she did the most dance. It was done by both leads together with the chorus. The dance was mostly tap style with a little jazz thrown in. Katherine did hold her own pretty well during this piece, although once again it was pretty easy to pick out the dance pro.
All in all I would say that this level of dance performance is pretty much in line with what most Broadway and movie musical performers do all the time. None of it involved a hard core dance role that might have been found in a musical like "Singing in the Rain". Most stage actors would be expected to dance with the same level of proficiency. Many of the pop singers that have appeared on this show have done as much or more dance as part of their stage shows and music videos. None of the numbers involved Ballroom or Latin style dance. If you wanted to disqualify contestants on the basis of this level of experience you would need to disqualify half of the contestants we've had on this show to date.
I do have to say that during the performance Katherine looked very comfortable on stage and moved very well. If you look at the video you can see that she has the basic talent to do very well on DwTS. If I had seen this video before the show I would have predicted that she would do well (and so would the odds makers have).