* Prices may differ from that shown
I have had the Palm Treo 750v for around a year now. It was provided by my company as a work phone, so I can't comment on price or individual data plans.
Originally the phone was provided to me as it said on the Palm website that Blackberry connect would work on it and I need to get my work emails on my phone, unfortunately it subsequently became apparent that this is not the case with this specific model. I have since found free software called Emoze which works fine with my work emails but I was disappointed with Palm for providing false information on their website.
That issue aside, I have been very impressed with the phone. The camera is not great compared with similar phones and if the camera is a feature you would use more than occasionally I would recommend considering another phone as you will probably find the quality is not good enough. However it's fine for taking photos of people to add to your phone book etc.
The general interface on the Treo is nice and easy to use and i like being able to use either the stylus or the buttons. The keypad is very good - I have no trouble typing on it although if you had very large fingers you my find you would occasionally hit the wrong key. It's great being able to type texts with a qwerty keypad, although I work in IT so I type constantly all day long.
I have the SPB phone suite which allows you to change the layout of the today screen and have a more detailed battery life indicator which is very handy.
The Treo came with Microsoft Office Mobile on it which is very good - easy to use, especially with the full qwerty keypad.
Battery life seems to be acceptable - bearing in mind my email software is constantly connected I get around two days from a full charge with say four or five short calls per day.
The Treo is small enough to fit into a pocket and not overly heavy. I recently felt the weight of an newer HTC phone and was surprised how much heavier it was than the Treo, although I'm not sure how the weight compares to a Blackberry which I think would be the closest competitor. It fits in the hand very nicely and holding it and typing with one hand is no problem. I know I've mentioned the keypad a few times but it's proved to be a real bonus for me and I'd now rather have that than a phone with complete touch interface rather than a real keypad.
It also seems to be fairly resilient to bumps and scrapes - I've dropped it a few times and I have two small kids so it's been tested a few times and so far survived well.
There is some great software available for the Treo as it runs on Windows Mobile 6.1 so there's plenty of choice.
There are a couple of minor niggles I have found -
1) The headphone socket is 2.5mm not standard 3.5mm. fine if you're happy to use the generic earphones that come with the phone, not so great if you want to use your own. I assume adaptors are available though.
2) Using the OK button to close an application (the standard way to close one according to the manual) seems to leave the application running in the background more often than not. Using the stylus to click the X in the top right hand corner closes it properly. The SPB phone suite I use fixes this issue and you can just hold down the OK button for a list of running programs to close them down so it's not a massive issue.
Other than those two issues and the camera quality, if you're looking for a good phone with a full qwerty keypad, Bluetooth, internet etc and don't plan to use Blackberry connect I would recommend it highly. When I get and upgrade option I will probably stick with the Treo and go for the Treo Pro.