A few of my friends had the P900 so I was able to compare the P800 and the P900.
I will be making comparisons the both the P800 and P900 just because there are certain things that I feel are relevant to both older siblings.
Now with my P910 I think I can make a pretty good comparison to the phone I've had the longest (almost 2 years)... my beloved P800.
First, the obvious... the screen... it's a whole lot better, even compared to the P900. Contrast is much better and colors are a lot more vivid.
The numeric keypad on the P900 feels a bit better though, more tactile feedback, and it's easier to feel the keys. The P910 keys are good and big, but relatively flat... so there is a greater chance of hitting the wrong key. But it's not that bad... the P900 keypad was just a bit better. I do like the white backlights however. I won't discuss the keypad on the P800 cuz that was just pathetic...whoever designed the P800 keypad should be shot!
It's still running UIQ 2.1 so no jump over the P900. Small things were added.. a dedicated PDF viewer (although even the P800 could view PDFs, it didn't have a cute icon for the app)
Other apps on the CD are mostly demo apps so those are useless.
The sync application is now unified for the P800/900/910 the latest version can be downloaded from SonyEricsson's site.
Now for famous thumb-board. It works really well. Feels weird at first. Specially since I got used to using the P800 without the keypad... I'm still faster with my stylus though. But the keypad is fun to use, entering long messages is a lot easier now. The flip is a lot stiffer than the one found on the P900, but you can still open it with one hand.
One thing that I did notice however is that the phone itself is a lot faster than the P800. I haven't been able to confirm the CPU used on the P910 yet, but I'm guessing it's that the P910 now uses faster memory... probably the same type found on the Duo Pro sticks.
On board memory is heaven... it's like moving from a one-bedroom apartment to a 2-storey mansion! Handy Day memory bars look empty even with most of my apps installed.
The biggest problem I had was transferring my SMS from my P800 to my P910 (ya, ya... I'm an SMS hoarder)
Ok... that's enough of the good news. There are a couple of glitches that I already found.
One being that the P910 has issues with the HBH-30. Since the P910 now supports the new Handsfree/Headset Bluetooth profile, older headsets seem to have a problem keeping paired. My headset works occasionally...but it loses it's connection often now so I can't initiate a voice call from it. According to the new and improved SonyEricsson call centers, the HBH-30 is not compatible with the P900 or P910...duh... whatever. (If I find out that those morons are working in Convergy's, I'm going over there and I'm gonna beat them with a stick!!! HAHAHAHA!)
The Bluetooth issue is the only serious bug I've found so far... the second bug I've found is fixable.
I had issues syncing with Outlook XP. Again, SE Call Center help...was of course... no help at all. I found the solution though, download the latest SP3 for Office XP and it fixes the sync problem. I can't speak for Office 2003 users, but I'm guessing if you have sync problems, get the latest Service Pack from Microsoft.
Over-all, the P910 is a great upgrade to P800 users. P900 users, well, I'd recommend just holding out for the next one... or sell your P900 and add more for the P910. But unless you plan to get the new Duo Pro sticks, the P900 is good enough for most people.
**Wishlist: WiFi, and cheaper memory sticks! (Oh, the P910 comes with a 32MB Duo PRO stick...by... Sandisk! hahaha! I guess Sony didn't meet their deadline)