I am a longtime Palm user - most recently (and on-going) a Palm Tungsten C.
So - I am comparing with what I think was (and to some degree still is) one of the best PDAs for relatively heavy mobile use (good bright screen, keyboard built-in, built-in 11b, fairly fast operation, good base memory plus MMC slot, Infrared - but no Bluetooth).

Some of my dislikes/suggestions below might just be me not finding out how to do some things with the GUI - but fun learning so far.

Country: UK
Purchased From: Nokia via Web (shipped from Belgium)
Purchase/Arrival Date: 26/Jan/06 - 31/Jan/2006

Likes:
Screen size
Full-screen zoom button
Font size increase/decrease via button
11g wireless
Openness

Dislikes:
Mail
No option for Auto BCC
- Default and override per mailbox/message
Alternate outbound server
- Roving user accessing home mailbox but WLAN specific SMTP server
No (obvious anyway) mark multiple messages for delete
- Selecting unopened obvious spam for deletion is painful
Modify default for deletion to be local only since it seems to insist on a live connection when requesting delete on both (Palm does not - it remembers and syncs next time)

Time format
- Prefer 24-hour clock rather than AM/PM in all places where time appears

Connectivity
Shame there is no infrared both for beaming data between devices and as home equipment remote control.

TCP/IP access via USB (PPP over USB via router software on PC) for low power network usage or if with laptop in office without wireless connection (I do this on my Palm via 3rd-party software on PC - but basics are already in standard PalmOS (PPP via USB).

Power
- seems to use it quickly - but waiting for a few more discharge/charge cycles to be sure
- power via USB ...

Newsreader
Doesn't honour font increase request

Chess
Allow tap for source and destination selection not just drag
Highlight computer last piece moved

Speed
Does seem slow - despite installing Dec/05 firmware update.

Favorite apps:
Browser