Massively has someone that likes this viewer and generally writes up good reviews. This one is a bit sparse, but they link to the Imprudence site’s notes.
Notice the word TEST in the title. This is a beta version viewer. They included dynamic shadows in this one. Then made disclaimers about it. So, if you want shadows use Kirsten’s S18 Viewer. See: New KirstenLee (215) Viewer Out – Review
They have a link into the AutoScript Tool at 3GreenEggs.com build into the viewer. Its good for simple scripts.
Other than that there does not seem to be much new in this viewer. Most of the update appears to be code catching up to SL’s code. I may wait for the final 1.3 version.
For more infomration and links on the ImprudenceViewer see: Second Life Viewer: Imprudence 1.2 Review