Jeff Kirvin of the excellent Writing on Your Palm switched from a Tungsten E to a T5 and posted a lengthy review on his blog:
"The T5 isn't perfect, but it's damn close. I can hear the howls of derision already, but hear me out. I've said before the T5 isn't the perfect übergeek device, but for a writer on the go, it's great. It may not have WiFi, it may not have a vibrating alarm, but it's got what counts."
Also here's a link to Julie's of The Gadgeteer review mentioned in his writeup which has a detailed review of the specifications and measurements.
I also found BargainPDA's review.