Customers most agreed on the following attributes:
It's great to have a pile of batteries in your bag to keep your speedlights running fast. (now I need a bigger charger)
Given the prices charged for the same battery in smaller packs, or other similar batteries, the price is incredible. The batteries work well. With the _really_ fast charger available elsewhere in the site, they work particularly well. I suggest marking them as sets (numbers, letters, whatever) and keeping each set to gether in use and charging, and I try to charge them all every month whether I use them or not. Hove only had them for 4 months or so, so no long-term results yet, but so far, they have worked perfectly.
These are very necessary to feed my Speedlite flashes. It is great to have a huge supply of these suckers around for traveling and extended shoots.