I did a quick analysis of the source code, it's very very simple code and looks harmless, however Newtonsoft.Json.dll could be rigged. (I don't have time to do a file integrity comparison of this version against the official downloadable version).

Why would anyone use a bloated external library to parse such simple json responses anyhow? A typical VB.NET programmer thing to do but then again I use VB.NET too.

I started of with something similar for the mtgox api, and I ended up with a semi-automated buyer/seller bot.