The film received mainly negative reviews with many critics blaming the film's flaws on Jennifer Lopez. Some film critics have expressed their surprise at the relatively high profile given to the Puchi character in the film (as compared to Nilda Perez's relatively subdued influence over Lavoe's career). The film was criticized for its formulaic writing and hollow character development. It received a 22% "rotten" certification from the entertainment website Rotten Tomatoes with the consensus being it "adheres to the most basic conventions of the musical biopic, rendering it indistinguishable from others of its ilk".

The film opened at #12 at the U.S. Box Office, grossing over US$3,254,000 on its three-day weekend, with a total gross of US $7,556,712. The film was screened in only 542 theaters throughout the United States, a substantially small number of theaters compared to number of theaters that The Bourne Ultimatum, which opened #1 at the U.S. Box office during its opening weekend, was screened in nearly 4,000 theaters. El Cantante made about US$6,004 per theater in its opening week. The films distributor, Picturehouse, has rearranged how the film is distributed in an attempt to target the film to its audience. Each film print cost Picturehouse US$2,000. Picturehouse removed El Cantante from theaters which showed softer sales while opening in more theaters where demand was high.

Released on October 30, 2007 El Cantante became a DVD hit. Peaking at #8 in the DVD chart, it grossed $16.61 million on DVD.

Willie Colon, Lavoes' long time friend and musical partner, was critical of the film, writing on his web site:

The Creators of El Cantante missed an opportunity to do something of relevance for our community. The real story was about Hector fighting the obstacles of a non-supportive industry that took advantage of entertainers with his charisma and talent. Instead they did another movie about two Puerto Rican junkies. The impact of drugs in the entertainment industry is nothing new; look at Britney Spears, Lindsay Lohan and Whitney Houston today.

Fans of the film point out that the film did cover briefly the issue about Lavoe not getting paid by Jerry Masucci. Eddie, played by Manny Perez, says to Hector:

"Jerry (Jerry Masucci) used to be a cop, then a lawyer, now he's a thief, robbing every Latin musician blind - but, he's all we've got."

Lopez responded to the criticism when interviewed by the Los Angeles Times : "I don't know what movie they want to see, because this is the truth."

Another controversy is the amount of screen time Jennifer Lopez has in the film. Critics of the film say that Puchi played a small role in Hector's musical life, while fans say the story is told from Puchi's point of view so she had to be shown as present in much of the film.

When commenting on the film, Lopez felt her performance should have earned Oscar nomination and blamed the Academy of Motion Picture Arts and Sciences for overlooking both the film and her performance.