I've tried to find english review or similar document about TekuTeku but all the reviews seem only to have the basic information like what the gadget is and how it works (calculates steps and raises little creature which becomes ugly and fat or cute and small depending how much you walk with the gadget - we know that already)
This is the official japanese page: http://tekutekuangel.jp/pocket.html
The VP seems to be sold in Japan alone, or with Nintendo DS "walk diary" software. The software also is sold alone without the VP.
When you buy Tekuteku from online store remember to check if it's only the VP or is it the "with DS Diary" bundle. (Yesasia sells only the bundle)
Looks like the VP is easy to use without the skill to read japanese but the software has quite a lot of text that isn't written with the "simplified" hiragana/katakana characters so it will be challenge to those who study japanese - like me.
Only page that explains something other than the basic info is THIS