Well this certainly is worth watching if you're a fan of Yoko. If you aren't a fan of Yoko or J-pop this is going to be very sub-par. The story (if I can call it that) chronicles Yoko's imaginary life immediately following the events of Gurren Lagann Season 1 (episode 1-27). We get some insight on how under her rough tough (albeit curvy) exterior that Yoko is quite "girly". After about Four minutes and Twenty seconds of Yoko day-dreaming she snaps back to reality (cut the J-pop) and continues on her way. This really is a shameless money grab in exchange for fan-service. That said it is all about Yoko Littner (and her apparent lack of clothing) and for that reason it is not only watchable but worth digging around for, if curvy anime chicks are what you are into (although this IS http://www.anime-planet.com so that would make sense).
TL;DR - As an Anime critic: 1/10
As a Yoko Littner fan: 9/10
As a Music fan: 5/10
As a animation critic: 5.5/10
Anime in 150 Words: Tengen Toppa Gurren Lagann: Kirameki Yoko Box ~Pieces of Sweet Stars~
Why 150? It’s a short. Not much to say.
Premise: This is a music video featuring the fiery redhead from Tengen Toppa. Equal parts music and career fantasy, it is a pretty entertaining five minutes.
Music: Fairly catchy pop song, but not one that stuck in my head. I think I watched the video about three times and was content to move on.
Video: The young woman changes outfits and careers as the song progresses, and it reminds me of the way that kids talk about what they’ll be when they grow up.
Audience: Most likely, fans of the main series, because I imagine there’s more significance if you know who is bouncing about and transforming.
Overall: If you like J-pop, you should take a few minutes to watch it- it’s a pretty catchy video.
I'm going to warn you once, and never again: This video is about delicious, womanly curves. Anybody who even attempts to tell you differently is on a cocktail of drugs.
The "Kirameki Yoko Box" is a character DVD featuring TTGL's very own Yoko Littner (yeah, you forgot she had a last name didn't you? I didn't) doing...well, it's very difficult to say what she's doing. This is not to say it loses point due to lack of plot--it's an AMV, for God's sake, what plot can one possibly expect from it--but it does make things super weird. What it boils down to is basically Yoko in various outfits and lifestyles never seen in the series.
Damned if they aren't some hot outfits, too. This is an official Gainax release, and they drew & animated it exactly as though this box set were part of TTGL canon. Remember the first time you saw Yoko's chest jiggle as she jumped? Or walked? Or turned around? Well strap in, cowboy, because that's what you'll be looking at for a full 4 1/2 minutes. If you're not interested in extreme amounts of fanservice--and if you aren't, we have nothing in common--then this is not for you. But if that's your game, and you remember how cool the TTGL opening sequences were, this is your Grail.
Unfortunately, what makes the box not exactly for me is the song. I love the TTGL soundtrack, and J-pop isn't nearly as abhorrent to me as to most straight-leaning American males. But the song ("S.t.a.r.S," performed by J-pop artist and Yoko's voice actor Marina Inoue) is so mediocre and caught up in the thrill of repeating the same techno dance beat over and over that it lost me. Luckily, it's still a fine track to zone out to while you scoop up some eye candy, which is really its entire reason for existing. Hell, the set even comes with two mixes, one of which is an instrumental version, so you won't even have to deal with Inoue yelling that "YOU ARE MY STAAAR" if you don't want. In terms of sound quality: what do you want? This is Gainax. Production values are high, and the song is well mixed to boot.
I've scored this one 10/10 for characters, because as much as I love Yoko's boobs (and also butt, never forget her butt), the cameos here are what make the video for any TTGL fan. Pretty much the entire roster of the Dai-Gurren Dan can be found somewhere, so it's like a scavenger hunt sometimes. My personal favorite, a rock band featuring Viral wailing away on lead guitar, was one of the most obvious ones, but it's neat to see Dayakka having fun on a saxophone and (later) discovering Kittan as a high schooler. If you're not familiar with the series and its characters, you won't get much out of it. But I assume that goes without saying, and that if you bought the Kirameki Yoko Box without watching one of the most celebrated shonen mecha anime ever, you might be kinda dumb.
Overall, this is a collector's piece. The box is visually fun, from the video to the art on the box itself; it fits nicely on your shelf with the "Alternate Works" DVDs and the collected manga. If you aren't hugely into TTGL, you should've quit reading four paragraphs ago and you won't like this; if you are, and can ignore a pretty annoying song for the sake of another neat twist on an already crazy anime, then the Kirameki Yoko Box is something you should definitely put on your wish list.