All my previous phones were made either by Nokia or Ericsson. I was generally happy with both brands. This is the first Ericsson phone I have since Ericsson and Sony merged their cell phone products.
The W810i has many nice features, and if you look at the specs, this is an rather impressive phone. However, after using it for couple of months, I was deeply disappointed with some of those features in practice. I'll try to summarize some of the good and bad sides, in no particular order.
The phone is relatively small. Not as thin as some other phones out there. My old old Ericsson phones (without Sony in the name) were actually thinner. But they had external antenna too, and no built-in digital camera.
The built-in digital camera is actually usable with its 2 mega pixels. It can even focus. As opposed to standard (for mobile phones) low resolution, fixed-focus cameras built in many of the older phones, this is a huge jump in quality. W810i even has light/flash thingie, which makes it even more usable. However, light/flash has to be turned on manually for each shot. It will not fire by itself automatically in low-light conditions. My guess is that this was deliberate design decision to extend battery life. There's 4x digital zoom, which is my only real objection in this area. If the phone had the real optical zoom, even with smaller range (2x or 3x) it would be way more usable than "fake" digital zoom.
"W" in the name comes from the "Walkman", I guess. In this case, "Walkman" refers to MP3 player. I haven't used it much, but it seems to be usable. Not really a replacement for your iPod, but it will do the job. The phone itself has no 3.5mm headphones connector. However adapter for 3.5mm connector as well as set of headphones are included with the phone. The headphones adapter also acts as a hands-free (it has microphone) and has a button for answering the calls and a clip. Included with the phone is a USB cable. For transferring your MP3 collection to it, I guess. Worth mentioning is that the phone has a speaker, so you don’t need to have headphones to listen to your MP3s. The quality of sound through bult-in speaker is not much though. But that's to be expected. All in all, very nice.
Phone comes with 256 MB memory stick. Which is more than generous, compared with my 6 mega pixel Canon digital camera that came with ridiculously small 16 MB SD card. 256 MB memory stick is more than enough for 2 mega pixel camera. It's kind of on a small side of things for storing your MP3 collection onto it. Couple of albums, and you'll start running out of space. If you want to use this phone as MP3 player, you'll probably want to upgrade to higher capacity memory stick sooner than later.
So far so good. Now some big disappointments. Bluetooth. One of the things I use on daily basis. Something all my phones simply must have, and it simply must work flawlessly. Well, it doesn't with this phone. I've a GPS that is Bluetooth enabled and acts as hands free, and can also access address book and SMS messages on the Bluetooth enabled phones. Most of the time Bluetooth with this phone works OK, except when it doesn't. The connection between the GPS and phone drops at random times. The phone ignores the fact that my GPS disconnected from it way too often, and still displays a small "using hands free" icon, even when my GPS was turned off (not there) for a long time. I have to power cycle phone in order for it to realize my GPS disconnected from it long time ago. I'm also using Bluetooth to connect to the phone from my laptop, in order to have Internet access when on the go and far away from Wi-Fi hot spots. Mostly works fine. However, if I have another Bluetooth device connect (for example hands free), the connection between laptop and cell phone will simply freeze. This phone is supposed to support connection to multiple Bluetooth devices simultaneously. In practice, it just doesn't work reliably.
The unreliable Bluetooth is obviously my biggest grief.
Another thing I don't like is the address book. It doesn't allow storing of multiple numbers of the same type under single name. If you know somebody with for example two cell phone numbers, you are out of luck. You can't mark them both as cell phone numbers. There's option of marking a number as home, work, mobile, fax or other. And you can have exactly one of each. There's no pager type, BTW. My old address book (which is also synced to couple of other devices) contained several entries that I had to modify in order to get them accepted by W810i. You can not store email and street addresses into the address book of this phone. These are very serious limitations that should make you seriously consider the usability of this device, if you need address book synchronization.
The two orange buttons are nice. However, way too often I end up pressing the "Cingular" button, and the phone happily connects me to the Internet right away. Luckily I have generous data plan (well, not really, I still have to pay to have it), so this doesn't really cost me anything extra. But if you don't have (or don't plan to have) good data plan, it should worry you. Be careful which buttons you press. The two orange buttons are very easy to press by mistake. The one on the right that connects you to the Internet much easier than the one on the left that starts MP3 player.
The last negative thing is relatively lower sound quality of phone calls than what I'm used to. I have a feeling my old Nokia (and older Ericssons, without Sony) were much better. Or it just could be that my hearing is slowly going south. Who knows.
Conclusion. This is very nice phone. However, if you plan to use some of the phone's advanced features such as Bluetooth, you may end up disappointed. Also, if you require advanced address book, you'll be disappointed with this phone too. W810i simply doesn't cut it in those two departments. On the other hand, if you don't care about those two particular features, you'll be very happy with this phone.