Although I do not own a PowerVR based graphics card for the PC, I was introduced to the power of PowerVR2's Tile based rendering with the SEGA Dreamcast so I can back up that the PowerVR is really a powerfull chip, even though the ATI 8500 and up have improved as far as power is concerned.
I wanted to post a link so that anyone could see some screenshots of SEGA's PowerVR2 based NAOMI arcade boards and the NAOMI 2 that uses dual PowerVR2+a Geometry co-processor for transform and lighting code named "Elan" along with 32MB system ram, 32MB video ram and 8MB sound ram. If you ever see Virtua Fighter 4 at a local to you arcade you will be able to see what I mean.
http://www.system16.com/sega/index.html
Aside from that, SEGA is planning to use a PowerVR based GPU in their up comming NAOMI 3 arcade hardware but there are no technical details yet.
Also whenever this GPU is released (prolly Dx10 hardware compliant) I hope that this will help them make a strong comeback to basically wreck havoc on the current default champs in the video card realm.