Unlike the Looney Tunes movie Space Jam where it had a mediocre reception but a very good box office performance, this film was met with an ok response from critics but bombed financially and to this day is pretty under the radar. That being said, I actually enjoy Back in Action quite a bunch as I felt it was more faithful to the zaniness and wittiness of the original Looney Tunes. While I don't think this movie is by any means a masterpiece, I think it's very underrated.
I think one reason the film was not received all that well is because....well, it doesn't really make much sense plot wise. After leaving Hollywood due to all the attention going to Bugs Bunny, Daffy Duck joins former stuntman Damien Drake Jr. (Brendan Fraser) and embarks on an adventure to find Damien's father, and the missing blue diamond. Along with Bugs and The VP of Warner Bros (Jenna Elfman), they try to obtain said diamond before The Acme Corp. does for their own sick purposes. However, I think you have to really be a big fan of Looney Tunes to accept just how ludicrous the plot really is. Some of the classic Looney Tunes characters either appear as small cameos or advance the plot in such odd ways, but again, they helps progress the film and play into the film's silly nature.
While the live-action characters played by Brendan Fraser and Jenna Elfman do fall a little short, the gags with the Looney Tunes are jam packed with slapstick, fourth wall breaks, pronoun trouble (heh, heh), and even some self aware moments, like a small banter between Daffy and Bugs on wild takes. Admittedly, not every joke does hit and the film does act a little too self aware at times, but it never distracts from how funny the other jokes are.
Adding further into the film, the animation was lead by former Disney animator Eric Goldberg, and it looks fantastic. It really does look like the toons are there with the live actors, and the animation on them is fluid and amusing in its own right. The voice-acting is also top notch, with the stand outs being Joe Alaskey as both Bugs and Daffy and Billy West as Elmer Fudd. They do a great job bringing the characters' voices to life and it's no wonder they still tend to voice them today (minus Alaskey though who sadly passed on).
To sum it all up, while the humor is hit or miss, the live leads are somewhat dull and the plot can be too ridiculous at times, Looney Tunes: Back in Action offers enough wit, lovable Looney Tunes chemistry, solid animation, and charming voice acting to make it an enjoyable experience that embraces how silly it really is. Apparently director Joe Dante hated working on the film due to having Warner Bros. be too demanding of changes and restrictions, but I think he succeeded enough to make a fun if not flawed film that at least gives a decent lime light to my favorite Looney Tune character, Daffy Duck. So I recommend this flick if you're in the mood for some weird but harmless Looney Tunes entertainment....oh yeah, and Steve Martin acting like a lovably cooky leader.