This Hayate movie can be viewed as an OVA as it doesn't really have anything to do with the main story line. Basically Nagi's group decides to end their summer vacation by visiting the Japanese countryside (apparently Ayumu has a summer villa). There, some extraordinary circumstances take place resulting in kidnappings, randomly appearing theme parks, and cameo appearances by lots of characters (some that are apparently manga specific).
This is not Hayate at it's best. The comedy is significantly below what was in either of the two TV adaptions and some of the personalities even seem a bit off. The plot doesn't help either with a predictable progression combined with unnatural elements (like the ability to erase specific memories). If you really want more Hayate, petition for another TV adaption so we can get more Hinagiku, and spare yourself an hour of disappointment.
Animation:
Hayate keeps getting face lifts, and this movie is no exception. Unlike the second TV adaption, this face lift is for the worse. Hayate's hair gets longer and his face makes him look even younger/less responsible. A lot of the other characters also get some changes including Izumi who suddenly gets much longer hair. I got royally confused at times trying to decipher whether the person on screen was either a modified TV character or a new addition.
For a movie, the quality is also abysmal. My latest movies at the time being Kara no Kyoukai and Eve No Jikan, this is so many levels below that it's somewhat pathetic. The colors are average (minus character shading differences from TV) but backgrounds are lacking in detail at times. Pretty much this entire section is sub par to the second Hayate TV adaption.
Sound:
The Movie has a nice paced OP (and does a decent job of recapping the entire TV series so far while at it) and a nice, upbeat electronic based ED with a pretty good melody. The BGM is somewhat comparable to the anime series though isn't used very often in this hour-long production.
The VA cast is identical to the TV series, and you can expect their performance to be on par with that version. If anything is disappointing, it's the limited exposure that Hinagiku gets.
Story:
This movie takes Hayate on a very "magical" tangent where many mysterious elements take place. He finds himself in the Japanese countryside where his master is dying of lack of iPhone reception (yes they actually refer to the device by name) and heat. After following a mysterious person, Hayate loses track of Nagi who, as usual, ends up "kidnapped". From that point onwards, it's very linear in progression and the climax/conclusion are all very predictable.
While the mystery is decent at the beginning, I soon grew tired of repeated elements and farfetched explanation of what was happening. The only worthwhile part of the movie was a tiny bit of new background information on Hayate. But it isn't worth sitting through Nagi's unusually high amount of complaining and whining.
Character:
Character relations are very very weak in this movie. The Hayate TV adaptions were great for balancing good comedy with light romance. Here, Nagi seemed overly ready to abuse Hayate, more so than is characteristic of her. It made it really hard to figure out whether the movie was between the two TV adaptions or at some other point in time.
As for the other characters, expect lots of brief cameos and a bit of Hinagiku. Unfortunately, you only get a brief glimpse of her tsundere feelings for Hayate. Ultimately, the movie is about Hayate's deep commitment to Nagi, though the execution doesn't make it very convincing.
Value:
This is a solid skip. Unless you absolutely are dying for some more Hayate, this isn't worth your time.