Williams excels as the gold-digging but possessive Sibella, bringing her lovely voice to bear on the passive-aggressive sentiments in “I Don’t Know What I’d Do.” ... Williams, Eller and Massey are a superb trio in the door-slamming and show-stopping “I’ve Decided to Marry You.”
— Terry Morgan at StageRaw.com
Williams makes a breathtaking Sibella, simultaneously wanton and vulnerable. With her sterling soprano and girlish recklessness, she offers a beguiling alternative to Eller’s chirpy and straitlaced Phoebe, who is equally alluring in her own way
— Jordan Riefe at HollywoodReporter.com
Driving Monty’s lust for a title and a fortune is his love for Sibella (played with great physical comedy skill by Kristen Beth Williams)...
— Jay Barman at SFist.com
Williams refreshingly adds the funny femme-fatale role of Sibella to “A Gentleman’s Guide” — her introductory song “I Don’t Know What I’d Do” is cute and fun, and she is absolutely pretty in pink. Forced to choose, this journalist would select seductress Sibella over prim-and-proper Phoebe.
— Don Chareunsy, Las Vegas Sun
All the while he has to juggle a mistress Sibella Hallward (a pitch perfect performance by Kristen Beth Williams) who is after more than his love...
— James Murray at ShowbizChicago.com
We find that he has a love, Sibella ( the adorable and very sexy Kristen Beth Williams), but that she desires a man of power and wealth.
— Alan Bresloff at AroundTheTownChicago.com
Kristen Beth Williams as Sibella Hallward is the perfect amalgamation of alluring yet aloof, sultry, yet slighting sophistry.
— Jennifer K. Hugus, losangelesbeat.com
The tall and curvaceous Williams also has a powerhouse voice with an impressive range. She’s a knockout on “Poor Monty” (“Poor Me”).
— Janet Preus, howwastheshow.com