^While I respectfully disagree regarding your criticisms of the characters, I thought it might be interesting to talk a bit more about the monsters, who really are the main spectacle of the film according to del Toro (and, in my opinion, they certainly are).
I was reading Pacific Rim: Man, Machines, and Monsters last night, which talks about the purpose each kaiju had in the film. The old phrase 'there are no small parts, only small actors' applies to monsters as well, so I thought I'd rank each of the 11 kaiju in the film in accordance with what I found their level of importance to be.
11) Karloff:
Karloff is only on screen for a few seconds, and even then only in shadow. Even so, it's tall, ominous presence in the prologue is reminescent of one of the heralds of the apocalypse; Karloff's purpose in the film is to show that the kaiju assault was going to continue.
10) Reckoner:
Reckoner, you might ask? Well, if you read Man Machines and Monsters, you'll know that Reckoner is the name of the kaiju that serves as the basis of Bone Town, a place of worship and black market dealings. Reckoner may be quite dead by the time we see him, but his remains serve as the basis for the most interesting set in the entire film. Reckoner's purpose in the film is to show how kaiju have become both figuratively and literally rooted in the culture of humanity. The fact that anyone would live in a place like that is a silent and ominous indication of how desperate things have become.
9) Scunner:
One of the kaiju fighting in the final battle, Scunner looks like an upgraded version of Knifehead and Axehead (indeed, to save money, Scunner used the same basic body as those two kaiju). One of the themes of the film is escalation; the Jaegers got better, so the kaiju got better, and Scunner is a very high end Category 4 kaiju, capable of taking a tremendous amount of punishment. Scunner appears just when the heroes are at their weakest and the hour is darkest, and his purpose in the film is to remind the audience that 'it's not over yet.'
8) Axehead:
As the very first kaiju we see, Axehead's purpose is obvious; he introduces what exactly the threat of the film is going to be. In addition to that, however, Axehead is the only kaiju to indulge in 'land mark stomping' by destroying the Golden Gate Bridge. Writer Travis Beacham wanted to avoid that particular cliche in Pacific Rim, but it was important for the audience to be reminded of Godzilla and the genre early on, in order to have a basis of reference for the rest of the film. Axehead delivers on what audiences expected to see in the first moments of the film, which makes his presence quite important.
7) Raiju:
Aside from Karloff, Raiju has the least screen time in the movie, but actually ends an important character arc for Raleigh. At the beginning of the movie, Gipsy's left arm is severed by Knifehead, which leaves Raleigh traumatized. When Raleigh suits up with Mako for the first time, he comments that he would rather take the right side, since his left arm hasn't been good since the incident where he lost his brother. In the final battle, Raiju effortlessly tears off Gipsy's right arm, leaving Raleigh helpless and forcing him to rely entirely on Mako to fight off Raiju and Slattern, which she succeeds in doing. It's a subtle and clever bit of writing that shows how much the trust between the two pilots has grown.
6) Bladehead:
Bladehead rampaging through a major populated area clearly showed the ineffectual nature of the coastal wall that was being built; the elaborate construction project was a political placebo designed to employ the dispossessed and provide false hope to the populace. Striker's fight with Bladehead proves to the public (and the audience) that the Jaegers are still needed, and can still hold their own against the kaiju menace. The scene with Bladehead is short, but critical to the entire plot.
5) Slattern:
As the biggest, baddest kaiju in the film, and the final obstacle for the Jaegers, the climax would not have worked without Slattern. If Scunner and Raiju had been the only kaiju guarding the rift, the fight would have seemed like a repeat of the film's second act with Leatherback and Otachi. In addition to being one of the final wave of kaiju, Slattern's presence and nigh indestructible nature illustrated that the aliens were now quite serious, even alarmed, at the resistance that the humans had assembled. Slattern's presence is therefore both terrible and hopeful; he proves that the humans were on the right path to victory.
4) Onibaba:
The unique-looking crab kaiju that pursues Mako through her memory/nightmare is the main introduction of her character arc and her relationship with Stacker in the film. When the audience is with the Jaeger pilots, the kaiju seem beatable, but when we are placed in Mako's position as a helpless child the scene takes on a dark and almost horrific turn. Onibaba's alien design contributes greatly to her unsettling nature, and while the scene is relatively short, it's one of the most important in the film.
3) Leatherback:
As one of the main kaiju in the film, Leatherback is the first real test for the team of Raleigh and Mako. Man, Machines, and Monsters notes that Leatherback was designed to test the resolve of the pilots; he serves as a 'wall' to prove that the heroes have what it takes to win. Of course, Leatherback is also responsible for disabling Striker, which forces the issue, and the injury to Herc that forces Stacker to get directly involved for the film's climax. Leatherback is also responsible for the destruction of Cherno Alpha, which actually had Otachi pinned down before Leatherback's appearance. In addition to all of that, Leatherback's defeat and Raleigh's insistence that they 'check for a pulse' showed the audience that he was no longer the cocky hotshot he was at the beginning of the film.
2) Otachi:
As the other main monster of the film, Otachi was designed to test the cunning of the pilots; she is one of the most intelligent kaiju we see, and proves to be the most difficult to defeat. Aside from the inner city brawl being a visual marvel, the fight with Otachi further tests the bond between Raleigh and Mako, showing that they can think as well as fight together. Otachi also goes hunting for Dr. Newton Geizler, proving that he was on to something with his 'kaiju drift' (Otachi may even have been under orders to eliminate him). Even when Otachi is (finally) defeated, her baby comes to life to menace Newt a final time (and provide a bit of poetic justice for Hannibal Chau). Otachi has been featured on many posters, press releases and commercials for the film, which served to solidify her status as the 'star' monster. One can't imagine Pacific Rim without her.
1) Knifehead:
Wayne Barlowe's design for Knifehead was the first kaiju to receive approval, and he definitely set the standard for what Pacific Rim's monsters were going to look like. Axehead, Bladehead, and Scunner all share design elements with Knifehead, making Knifehead the iconic kaiju for the film. Many kaiju in the genre have 'cute' elements to them, but there is absolutely nothing cute about Knifehead, who looks like a beast that climbed straight out of Hell. In many ways the Knifehead fight is the most intense in the film, because it is relentless, quick, and brutal. Knifehead showed the audience that kaiju fights were not going to be 'business as usual', and that every victory the Jaegers were going to have from that point on was going to be pyrrhic. In many ways, we have Knifehead to to thank for the film's more serious than expected tone.
So, that's my assessment of the kaiju; I hope you enjoyed it. It might be fun to see some of these creatures return for the sequel (such as Karloff), but with designs of this quality, I eagerly anticipate what new designs the artists will come up with next.
when i was a kid i thought he was cool lol 
i paid very little attention to anything related to this movie after is aw a teaser trailer. had no idea who was casted besides idris...
how the hell grown ups 2 beat it
stoned as hell the whole time.
