While billed as a movie, 'Birdcage Kingdom' is more of an extended episode of the TV series or a slightly longer OVA episode to compliment the XXXHolic Movie. The plot is little more than a chapter or episode from the manga or TV series just stripped of most of any depth either one might have.
It's a very simple and basic story of our heroes landing in one of the many "world of the week" seen in an adventure and fighting "big bad of the week" and resolving the plot at the end. Ideal for a short especially for one aimed at a younger audience over the older demographic the manga was written for, or the more all-age-demographic the TV show aimed for. While not really vital to see or read the source material of the movie you might be thrown off just a bit if you jump into this blind with no information. The movie does it's best to set the background of the plot by recreating the first encounter with Yuko who explains the needed sacrifice from Syaoran to save Sakura's life so even then getting lost in this movie should not be an issue.
The art and animation style is lovely, being it is a movie, with a beautiful and lively color pallet and really great and detailed art direction. With character desiigns by Yoko Kikuchi it plays a little more closely to CLAMP's signature art style but without the stiff limitations often seen. The cinematography also is pretty creative in the same right and shows a lot of high professionalism despite the short length. Proved to not be a throwaway B-Team project against the A-Team Holic project, I.G did clearly commit some resources sadly lacking from the TV series and later OVAs.
Much if any music by Yuki Kajiura is unfortunately tossed into the background and doesn't offer anything new for the franchise OST being just one or two simple pieces that you will barely notice, topped with some of the more iconic pieces such as "Break the sword of Justice." Likely in an effort to differentiate themselves from the TV series and to work around Kajiura's schedule they quickly edited a few pieces together and downplayed much of the original score. There is a opening theme by singer Kinya, who also provided the opening them songs for the TV series, but the song seems placed in the movie for the sake of having an opening theme given it plays for only five seconds and doesn't get it's full rendition anywhere in the movie it self. Yui Makino on the other hand gets to show her vocal talents with a full ending song, "Amrita" which is a nice ending theme to close out as the credits roll.
The acting in the Japanese version is very solid with a great cast of Miyu Irino, Yui Makino, Tetsu Inada, Daisuke Namikawa and Mika Kikuchi. The English dubbing however is less than stellar with a handful of good performances but two weak performances by Monica Rial as Sakura and Carrie Savage as Mokona. Like in the series these two are the weak links and are both a miscast for these important roles. Jason Libercht however does perfect to capture Syaoran and manages to catch what Irino brings to the role perfect. Same can be said of Chris Sabat as Kurogane and Vic Mignogna as Fai.
The TRC movie is visually beautiful and well made but doesn't really offer anything much more given it's strangely undercut running time, a suitable pre-show for the Holic movie but not much to give on it's own. Fans will enjoy it enough but there's not much to entice a general audience.