I ordered one of these batteries to test its performance. I was so pleased that I ordered a further two and have been using them almost daily for the last 5 months in my Sony GW66VE camcorder and newer AS30 action camcorder.
They seem to perform just as well as the original including giving a 'power remaining' icon in the display. They are a perfect fit in both cameras, don't become over-hot while charging or in use and last just as long. In fact, the battery is actually a higher-rated battery than the Sony original which is an added bonus.
Why pay more for the original manufacturer-branded batteries when these are available at a sixth/eighth of the price?!