Evolution tends to go in spurts. For a brief period of time, every possible configuration might be tried (Cambrian Explosion anybody?) and then eventually basic forms will be shaken out to be refined.
I'm kinda happy about how the market's being shaken up for once. I had regarded the whole PDA / Smartphone market with a certain amount of distaste and disinterest for quite some time. My old Viewsonic PDA died and I found I just wasn't using it for anything useful.. and then I ended up getting the Motorola Q because at least it had a decent web browser and keyboard so that I could text people instead of having to deal with my basic fear of telephones.
I'd been out of the Smartphone market for quite some time because it didn't make sense to me and offer the right combination of stuff. The first form factors (The earliest Treos, the phone-that-splits-in-half, and the attempt to add a fancier UI atop a standard phone keypad) were especially uninspiring to me because they offered a lot of cost for not a lot of value. The market wasn't there for them yet.
For a while, everybody really centered around the "Blackberry" formfactor. The higher-end Windows Mobile devices would have an accessory keypad underneath the usual touchscreen. Blackberries were designed to be the ultimate email device, so they had just the keypad and a scroller wheel and no touchscreen. And then Microsoft, who abhors letting somebody else in a market they want to dominate, took their standard-phone-keypad operating system and added a blackberry keypad to it.
So I ended up getting my super-thin Motorola Q in 2006 in the middle of this, which you can really classify as the "Blackberry" form factor. I'm not a super-huge fan of the form factor, but it's been a great little device. I credit the presence of a keyboard as being part of the appeal for me, given that I'm very textually oriented.
It's very effectively designed. They gave up width and length to make it the thinnest possible smartphone, which makes it feel good in the hands. They also value engineered it so that it was extremely inexpensive yet not a piece of crap.
The thing is, I found that when it comes to the ultimate email device, the Blackberry is better, largely because of the fancy server-push. But until RIM gives up on trying to control their experience and denying me the ability to write my own Blackberry apps and use my own mail server, I'll avoid them.
I haven't been following the situation so much recently, but it's quite apparent that there are two big form factors that are evolving right now... The first is the iPhone which, to be honest, doesn't interest me very much. Like I said, I'm very textually oriented and I don't think that they've quite solved enough problems with text input on a touchpad yet to replace a tactile two-thumb keyboard.
The other seems to be the flip-out keyboard form factor pioneered by Danger. Now, I've always regarded the flip-out devices where you have more than just a straight hinge as bad industrial design, solely because I could picture it breaking over time. However, I've come to realize that this isn't actually a problem. I was talking to a friend who was working at Danger and he pointed out that they've tuned the flip-up design to be so durable as to outlast the design lifespan of the phone by an engineering margin. Which makes sense... the early adopters inevitably have ADHD and will probably fidget with the phone by popping it open and closed. And it seems to be working in practice. Of the joint failures on my electronics, the hinge on an old Sony failed, whereas the flip-out joint on my Canon A95 lasted the life of the camera.
Now, the iPhone has incredible traction, largely because of the superior out-of-box experience it offers, especially for the sort of people who weren't smartphone buyers before. However, at this point in time, it doesn't offer me enough functionality, even though Apple is opening it up to external applications.
I've got a few predictions for the future about mobile phones and, by extension, all ubiquitous computing devices. One of them is that, given that the cost of adding many features (like cameras on cellphones) becomes so low that the penalty for not having that feature is higher than the cost of adding them. Especially when the not-totally-apparent benefits become visible.
I'm pretty sure that GPS and a touchscreen are going to be next to follow the camera. The GPS is a tricky one, because there need to be applications for a location-enabled phone that you wouldn't get out of a car GPS, but I've got a few things to try in the back of my head. Clearly fully-integral GPS is optimal because it's not going to be totally cool until it's on almost full time.
But the touchscreen is easier to predict. See, both the trackball on the Blackberry Pearl and the D-pad on most other devices have drawbacks. When I switched back to a touchscreen phone, I found myself totally annoyed while using my Q. I still do a lot of button usage on my new phone simply because it's tactile. Given that the Windows Mobile experience is not thumb-enabled, I find that it's easier for a quick email check to push the email button and use the directional pad instead of trying to pull out the stylus. I suspect that, especially with a slightly bigger screen, the stylus is largely optional but the touch screen isn't. At the same time, I'm not at all certain if the touch screen can completely replace buttons for all people.
See, even if you still have buttons, it's too useful. Consider the blackberry format. The biggest downside is that the keypad to dial is embedded into the rest of the keypad... but a touchscreen set of big keys would be much more convenient. I'm also picturing something like the flip-phone design with two touchscreens and no keypad, with maybe tactile bumps for the buttons.
Personally, I think that the dumbest thing that the Windows Mobile and RIM blackberry market is doing right now is trying to compete head-on with the iPhone. Take, for example, the HTC Touch. Adding a little bit of external code is not going to get you far enough away from the stylus/keyboard origins of Windows Mobile enough to get a useful product. Sure to access what's wrapped up with the fancy new UI, things are iPhone slick, but after you leave the confines of what HTC hacked together, it's Windows Mobile and really requires a stylus and a keyboard.
The part that's really funny about the slide-out form factor is to compare it to the earliest Windows CE clamshell devices and the phone-that-splits-in-half Nokia 9000 device. The current form factor is much closer to the clamshell design than many of the intermediate steps. The big change was just rotating the display 180 degrees.