I haven't used a smartphone outside the US, though international use is a major factor I'm sticking with Cingular (runs on GSM) rather than switching to Verizon (CDMA). I have used a Motorola v180 (regular flip-phone) in Thailand with a SIM card I bought there...
Anyway, my current phone is a Nokia E62, the Cingular-locked, WiFi-less version of the Nokia E61. The Nokia E61 should be available unlocked and with quad-band GSM (so works anywhere with a SIM card); it also has WiFi; ~US$400? Runs on Symbian O/S.
My previous phone was the Sierra Voq, which is triband GSM (should work on most GSM networks, but check, e.g. on GSMworld.com). It runs Windows Mobile 2003, and is a decent/good phone. Unlocked for ~US$100 (no carrier picked it up, so Sierra discontinued production). There are two versions, one for North America (available at Amazon.com) and another for Europe (which is more common on eBay). It has a nice flip-QWERTY keyboard.
As the above examples show, an unlocked GSM phone is your best bet. I have written reviews for the v180, Voq and E62 on Amazon.com (I know, shameless plug, but better than repeating my comments here!)
p.s. In case you didn't know - triband or quadband refers to the frequencies at which the phone can operate, 850/900/1800/1900 MHz. See GSMworld.com for more information.
I currently live in New Zealand and come back to States a lot and do other travel so am looking to buy one, excellent all around phone that I can use for everything - calls with a local SIM card, video/pics, wi-fi if possible, etc.. I am on a budget but want to invest in one all around phone so I pack less while travelling round but also want internet access
I am clueless on the new wave of "Smart" phones, pda's, etc.. as well as how I go about buying a phone while home in the US without having to buy a big 2 year contract as I really don't want to mess with roaming in NZ and US. I have prepay SIM card easy enough in New Zealand but would like to have one phone I can take with me and use everywhere. I have read some about the locked /unlocked issue and don't understand what I need to do to get what I need.
Any help would be so appreciated as I want to get this sorted in next few days as I am currently phoneless. Was thinking could buy a good phone somewhere and a SIM card for US to start with and just plug my NEw Zealand SIM card in when I get back there and be sorted.