I purchased this battery to replace my PSP 2000's stock battery, which, after 18 months, can't last more than an hour. This 2200 mAh battery definitely increased my PSP's life between charges - there's no doubt about that. I haven't been using it long enough to approximate how long, but it's a huge improvement. Whether that's due to the 2200 capacity, or just being a new battery, or both - it's nice not having to play while plugged into the AC adapter.
I quickly noticed a problem though when I first started using it. Every once in awhile the PSP would cut out and go completely dead - even when it had a full charge. I thought maybe the battery was faulty, but it would always turn right back on and show plenty of power. I later realized it happened when the back of the PSP received any sort of bump or tap, like if I sat it down on a table or something, and figured out that the battery was losing connection with the copper pins. When I opened the battery cover it seemed to fit well enough, but it must have been loose just enough to lose connection. I fixed the problem by putting a thin piece of cardboard under the cover and pressing it back on. This seems to keep more pressure on the battery and now it takes all sorts of knocks without powering down.