In terms of application speed the Blackberry, i-mate, and particularly the O2 with its 520MHz processor, are the fastest phones we reviewed. The Treo, Nokia, and Sony are not too bad either but the Motorola can be annoyingly slow at times.
The NEC and Siemens are a lot more limited in terms of processor and their applications, so they perform quite well.
None of the phones are what you would consider small. They have had ample space to implement a decent antenna and all the phones offer reasonable signal levels in many of the poor reception areas we tried, but bear in mind that there were four different carriers used among them.
If you are interested in the concept of video calls offered by the Motorola and its 3G functionality you should be aware that this is only available in a limited area. If you do drift outside 3G coverage, the phone roams over to another carrier so you then lose the extra features of 3G, such as high-speed data transfer and video.
Audio performance for the phones was quite good, with the O2 and i-mate offering the best sound quality. The Motorola was loud enough, but at times it appeared that the processor could not keep pace when playing back MIDI files causing it to sound out of tune, like an old tape player with a flat battery.
Contact Management and Applications
A full listing of the contact management features can be found in the features table but it is worth noting that the NEC was the weakest, and the Motorola's applications were also quite sparse.
The Siemens was surprisingly good but then it does use Blackberry applications for a lot of its functionality. The Blackberry and Treo have a broad range of features and applications, and the Sony is also quite accomplished. The best in this class had to be the O2, i-mate, and Nokia which are remarkably strong in terms of flexibility and features.
Although it is not quite available yet, you must also check out the next HP iPAQ 6500 - it is the size of a Blackberry 7230, but so much more capable; quad-band phone with EDGE, 1.3Mpix camera & LED flash, Bluetooth (no WiFi), GPS!!!!, and the usual PPC2003SE stuff (hopefully upgradeable to WindowsMobile5.0 in Oct or so).
http://www.brighthand.com/article/iPAQ_hw6500_Coming_in_September?site=SmartPhone
http://davesipaq.com/news/ipaq_hw6500_comparison.html
And here is a link to some recent forum comment about the size (smaller than a normal iPAQ), battery life (better than a normal iPAQ, not as good as a Blackberry!) and built in keyboard (very similar to Blackberry).
http://davesipaq.com/forum/showthread.php?p=35358#post35358
It is already released in Germany & UK (in theory at least!) and I'm hoping to see it in Australia in Aug or Sept..