The show focused on the romantic and personal lives of the main characters, often using legal proceedings as plot devices to contrast or reinforce a character's drama. For example, bitter divorce litigation of a client might provide a backdrop for Ally's decision to break up with a boyfriend. Opposing legal arguments were also frequently used to explore multiple sides of various social issues.

Cage & Fish (which becomes Cage/Fish & McBeal or Cage, Fish, & Associates towards the end of the series), the fictional law firm where most of the characters work, is depicted as a highly sexualized environment, symbolized by its unisex public restroom. Lawyers and secretaries in the firm routinely date, flirt with, or have a romantic history with each other, and frequently run into former or potential romantic interests in the courtroom or on the street outside.

The show had many offbeat and frequently surreal running gags and themes, such as Ally's tendency to immediately fall over whenever she met somebody she found attractive, or Richard Fish's wattle fetish and humorous mottos ("Fishisms"), ran through the series. The show used vivid, dramatic fantasy sequences for Ally's and other characters' wishful thinking; particularly notable is the dancing baby.

The show also featured regular visits to a local bar where singer Vonda Shepard regularly performed (though occasionally handing over the microphone to the characters). The series also took place in the same continuity as David E. Kelley's legal drama The Practice (which aired on ABC), as the two shows crossed over with one another on occasion, a very rare occurrence for two shows which aired on different networks.

The show's ratings began to decline in the third season, but stabilized in the fourth season after Robert Downey Jr. joined the regular cast as Ally's boyfriend Larry Paul. However, Downey's character was written out after the end of the season due to the actor's troubles with drug addiction.

The show was canceled after a significant ratings drop during its fifth season, which saw many regular characters disappear from the series without explanation (also a problem with David E. Kelley's shows Boston Public, Chicago Hope, The Practice and Boston Legal [to an extent]), and the novelty of the show wore off.

Despite its success, Ally McBeal did receive some negative criticism from TV critics and feminists who found the title character annoying and demeaning to women, and specifically professional women, because of her perceived flightiness, lack of demonstrated legal knowledge, short skirts, and extreme emotional instability. Perhaps the most notorious example of the debate sparked by the show was the June 25, 1998 cover story of Time magazine, which juxtaposed McBeal with three pioneering feminists (Susan B. Anthony, Betty Friedan, Gloria Steinem) and asked "Is Feminism Dead?". In episode 12 of the second season of the show, Ally talks to her co-worker John Cage about a dream she had, saying "You know, I had a dream that they put my face on the cover of Time magazine as 'the face of feminism'."

Ally McBeal was a heavily music-oriented show. Vonda Shepard, a virtually unknown artist at the time, was featured continually on the show. Her song "Searchin' My Soul" became the show's theme song. Many of the songs Vonda recorded for the show were covers of old songs with lyrics that paralleled what was happening in the title character's life onscreen. Old songs recorded for the show include "Both Sides Now", "Hooked on a Feeling", and "Tell Him". Besides recording background music for the show, Vonda would also appear in the show (usually near the end of the episode). Vonda would be seen playing at the local bar in which Ally and her fellow workmates regularly visited after work and would even have dialogue in some episodes. Due to the popularity of the show and Vonda's music, a soundtrack titled Songs from Ally McBeal was released in 1998, as well as a successor soundtrack titled Heart and Soul: New Songs From Ally McBeal in 1999. Two compilation albums from the show featuring Vonda were also released in 2000 and 2001. Other artists featured on the show include Barry White, Al Green, and Tina Turner. Josh Groban played the role of Malcolm Wyatt in the May 2001 season finale, performing "You're Still You." The series creator, David E. Kelley, was impressed with Groban's performance at The Family Celebration event, and based on the audience reaction to Groban's singing, Kelley created a character for Groban in this finale. The background score for the show was composed by Danny Lux.

Due to music licensing issues, none of the seasons of Ally McBeal were available on DVD in the United States (only 6 random episodes can be found on the R1 edition) until 2009, though it has been available in Italy, Belgium, the Netherlands, Japan, Hong Kong, Portugal, Spain, France, Germany, the UK, Mexico, Taiwan, Australia, Brazil, and the Czech Republic with all the show's music intact since 2005. In the UK, Ireland and Spain all seasons are available in a complete boxset.

20th Century Fox released the complete first season on DVD in Region 1 on October 6, 2009. They also released a special complete series edition on the same day. Season 1 does not contain any special features, the complete series set however does contain several bonus features including featurettes, an all-new retrospective, the episode of The Practice that Calista Flockhart guest starred in and a bonus disc entitled "The Best of Ally McBeal Soundtrack". In addition, both releases contain all of the original music. Season 2 was released on April 6, 2010. Seasons 3, 4 and 5 will all be released on October 5, 2010. Season 1 and 2 are also available on the U.S Itunes Store.