So, I just downloaded and skimmed over the vocaloid concert mentioned on front page a few days ago. For those interested, I snagged it off animetake:
http://www.animetake.com/hatsune-miku-concert/
I don't know how to browse nico, but if someone wants to directly link the stream in addition to rips, go ahead.
My first thought is, "maybe you just had to be there". For the most part, watching that performance is no different than watching music vids- if anything it's less so since there's little to no evironmental detail.
The choreography is a little tedious. It's more or less the same 5 dance steps put to slightly different beats. Furthermore, for the most part it's just one girl dancing by herself. Choreography is most interesting when showcases interaction between multiple people or props. There were a couple of duets, I noticed a Miku/Luka duet, a Rin/Len duet and I think two Miku/Rin duets- these were a lot more interesting to watch than most of the solo acts.
Two of the more entertaining songs were #13-14, starting at 0:37. The first I don't know the name of the song, but Miku was wearing cat paws and dancing accordingly; the second was PoPiPo, and Miku was wearing an imp/devil costume and had much more exagerated movements.
I thought that Luka was the real highlight of the show; she entered at 1:08. Her dancing was a lot more intriguing that Miku. He movements were bigger and crisper than Miku, and she spent a lot more time stationary, giving quality contrast when she does move. I also think the physics of her outfit are more entertaining to watch, and prefer her technologically superior voice, but those are more subjective evaluations.

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