Joan Rivers is one of those celebrities swathed in preconceptions. Admit it -- you either like her, can't stand her or are completely baffled by her actions or popularity.

If it isn't her bracing personality and comic style that get to you, it's her endless plastic surgeries that have turned her face into an unrecognizable version of what she used to look like. That is the Joan Rivers we know and think of in mainstream culture.

Rivers has had a lengthy career spanning decades, and Joan Rivers: A Piece of Work is a new documentary about Rivers that doesn't shy away from those preconceptions. While it could have dug deeper into Rivers' history, the film works best when embracing the viewer's judgments. The end result is a portrait of a much-mocked and maligned person that is thought-provoking and entertaining, despite being a bit too superficial at times.

A Piece of Work chronicles a year in the life of Rivers as she attempts to make enough money to support herself, her staff, family members and the myriad of others she writes checks for each month.

Rivers is upbeat that the year will be fruitful and turn her career around. She's got a new play opening in London and possibly New York, if it does well across the Atlantic. She's got an appearance on Celebrity Apprentice that she's leery of, but the pay is good and anything that brings her into the spotlight can't hurt her future schedule.

Rivers has gotten less popular with each passing year, replaced by lesser, younger copycats such as Kathy Griffin. Rivers is a complete workaholic and her biggest nightmare is to have no bookings. A blank monthly calendar is a knife to her heart.

Her fear of having nothing causes her to accept any and every invitation that comes her way. Whether it's hocking books, jewelry on QVC or taking pre-dawn flights to a wintry outpost in Wisconsin she's never heard of, if someone is paying, Joan is interested. As long as she gets to keep telling jokes and making people laugh, it's all worth it to Rivers.

The documentary consists of clips from various stages of Rivers' career to her cracking wise about everything around her, sometimes pointedly at herself. Nothing seems to be off topic, including her obsession with plastic surgery, her complicated relationship with daughter Melissa and the destructive loneliness that absorbed her in the aftermath of her husband's suicide. All juicy topics broached in the film, but some were worth exploring further.

The current Joan Rivers, despised by critics and mocked by the public, actually deserves respect for what she did in her early days as a female stand-up comic. She was not only groundbreaking, but she was anointed by the king of late night TV himself, Johnny Carson, and named the permanent guest host for the Tonight Show. When she left NBC for a deal with Fox to host her own talk show in 1986 -- it was all downhill from there. Carson turned his back on her, the show was swiftly cancelled and her husband Edgar's suicide all followed in rapid succession.

The documentary works best when it focuses on its attack of the self and show business through Rivers' life story. Rivers' career is past the 40-year mark, and that's kind of surprising considering the insecurities that are shackled to her.

Whether it's the self-image surgery issues or fearfulness of the viciousness of critical barbs, Rivers is wrapped in her insecurities. But no matter how many times she's slighted, insulted, made fun of and knocked down, she gets back up to try again. She's still ravenous for success and acclaim at the age of 75, and that's admirable for a performer.

The film could have used more older, archived material interspersed with the present day footage of Rivers. Some viewers might only know her from her current image and could have used a bit of the past to create even more of a context to the idea how important Rivers is to female comics.

I would have loved to have seen more appearances with Carson or other clips of her stand-up act. It's also a shame other comics weren't in the film to talk about Rivers. Only Kathy Griffin and Don Rickles show up to briefly talk up Joan. More comics would have served to validate the docs premise that Rivers was a groundbreaker, important to the history of comedy.

A Piece of Work reminded me of a similar (and better) documentary from 2000 called The Eyes of Tammy Faye that tried to reveal an unknown side of televangelist Tammy Faye Bakker Messner. Both films are about women you think you know through their reputation via gossip and mockery. After the films are over, you not only know more about the person and their life, you might feel a little bit of sympathy for them as well. Tammy Faye and Joan have a lot in common and these documentaries are similar in tone and in story.

The shock that comes out of A Piece of Work is just how likable Rivers is. Yes, she's harsh, brash, vulgar, blunt, opinionated and with a perpetual chip on her shoulder. She's also incredibly giving, loyal to those around her and brutally self-deprecating. I don't like her comedy more after watching A Piece of Work, but I do appreciate what she's done in her career, her relentless drive and never-quit spirit.

Joan Rivers: A Piece of Work is a profane, blistering at times documentary that looks at two key subjects -- Joan Rivers and show business. When it's over, many of the opinions you had of Rivers might be laid to waste with new ones in their place. Rivers likes to joke around that critics always put an adjective in front of her name, and it's never a good one. Here's a positive adjective for Rivers to describe the documentary about her life: illuminating.