The Treo 650, announced earlier this year, is basically an evolutionary revision of the highly popular Treo 600 [Can it really be nearly a year since we reviewed the Treo 600? - Editor]. At a cursory glance, you wouldn't think much had changed - and that's a good thing, because there was no reason to fool around with the Treo 600's basic design, a very successful balancing of the sometimes conflicting requirements of a PDA and a cell phone.

The alterations that PalmOne made addressed most, if not all, of the Treo 600's most glaring flaws.

Screen and keyboard upgrades
The most immediately noticeable improvement is the display. The Treo 650 boasts a brilliant 320-by-320 screen, compared to the old-style 160-by-160 resolution of the earlier model. When I reviewed the Treo 600, I rationalised this shortcoming by noting that since the screen itself is considerably smaller than that of a conventional Palm device, the lower resolution wasn't a big deal. And in the year or so that I lived with the 600, its screen never bothered me.

But having spent time with the Treo 650's new and improved screen, I can't imagine going back. It's somewhat akin to the way watching high-definition TV spoils you for old-fashioned standard-def programs. And while you're most likely to appreciate the improvement if you frequently use your Treo to play games or view photos, you'll notice it even if you're simply looking up a contact or an appointment.

Another significant upgrade that most users will applaud is the design of the thumb keyboard. The Treo 600's keyboard, with its raised, rounded keys, was by no means a disaster. But it wasn't a touch typist's dream, either. Because of the Treo 600's relatively narrow form (part of why it felt so good to use as a phone), the keys have to be close together; and truth be told, it was sometimes easy to slide off the key you wanted.

The new model's keys have small raised edges, so it's a lot easier to maintain a grip on them. As with the display, I didn't really mind the shortcomings of the Treo 600's keyboard; it was adequate for the small amount of typing I do on my handheld. Now that I have something better, though, I wouldn't want to go back. Certainly anybody who's serious about managing e-mail on a handheld will appreciate this improvement.

A better camera, a removable battery
The Treo 600's camera was another weak spot. It could take an adequate photo outdoors, in good light; but images captured indoors, even in decent light, were generally pretty pathetic. In poor light, the camera was basically unusable.

The 650's camera doesn't improve on the VGA resolution of its predecessor; but it definitely has a better sensor. Indoor photography is no longer out of the question. It also has a 2X digital zoom (the 600 had no zoom) and can capture video. I wouldn't buy the Treo 650 because of its camera, but if you want to snap the occasional image it gives you a better chance at getting a decent shot.

The last of the major upgrades is the battery: The Treo 650 sports a removable rechargeable battery, which means you can charge and carry a spare. Now, the older model's rechargeable battery is no slouch - many a time it lasted an entire weekend for me - but being able to take a spare along is a big plus when you plan a couple of days of intensive use before you can recharge.

Other improvements: An MP3 player (not that I'm big on playing music on a PDA, but I suppose some of you might care); and Bluetooth, for those who want to use a Bluetooth headset.

Missteps
What didn't PalmOne do right with its latest Treo? Those of you who visit this site regularly may already have heard about the problem with the Treo 650's memory. The good news: The device uses flash memory, so if its charge runs down it doesn't lose your data. But the switch from dynamic RAM, which is what the Treo 600 uses, entailed a change in the file system, which now requires more space to store the same amount of data.

Since both models are a bit short on memory to begin with, this is a problem. (You get a grand total of 32MB, of which only 23MB is available for apps and data on the Treo 650, less than the 24MB on the 600.) To compensate, PalmOne is < ahref="http://www.techworld.com/mobility/news/index.cfm?NewsID=2712">offering a free 128MB Secure Digital memory card to Treo 650 purchasers.

In a perfect world, the Treo 650 would have Wi-Fi. The GSM/GPRS version of the Treo 650 will at least have broadband support in the form of compatibility with EDGE, the next step on the GSM/GPRS data roadmap. This will make for speedier e-mail downloads and Web browsing on GSM/GPRS carriers that have implemented EDGE. [In the US, this includes AT&T, but in the UK there are no signs of commercial EDGE services - read our rant on the subject - Editor]

[Since this review was written, several users have reported problems with the Treo 650 microphone to a Treo discussion board. We suggest keeping this in view]

We assume that Orange (who offered the Treo 600) will be offering the 650 in turn. In the meantime, it can be pre-ordered at Expansys.

OUR VERDICT

Check the price and contract details in the new year, as this will not be a cheap phone (probably selling for something like £380 the 600 currently sells for SIM-free). Expect this to be a reliable replacement for a trusted performer.