[Touch Diamond, MDA Compact IV General] P996:
I have the iPhone and the Diamond and I've been also involved in iPhone independent software development too, so here's my opinion:

1. the touch functionality/usability of the iPhone is the best, right now there is no phone WORLWIDE which comes even close to the usability of the multitouch display of the iPhone. Compared to the iPhone, Touchflo3D is a joke regarding how it works(it looks great though). The iPhone touch functionality doesn't show ANY lag or something similar, everything works very smooth and intuitive, definetely the best finger touch usage phone available so far. If people say that Touchflo3D works similar or even better than the iPhone touch functionality, they don't have a clue about it(or are just not willing to admit it for whatever reasons).

2. the Diamond looks much better than the iPhone in my opinion, maybe it has also to do with the fact that the iPhone is the "older" phone. The Diamond definetly has a higher "sexy" factor than the iPhone.

3. the iPhone display is a treat when it comes to watching videos/movies/TV shows, it is very similar to the iPod touch display and absolutely great. Watching videos with the Diamond and Coreplayer somehow gives me a headache, the Diamond's video performance is still not really satisfying which may also have to do with the VGA resolution.

So for watching videos, YouTube stuff, etc., the iPhone is definetely the better choice.

4. I can't say much about the battery life of the new 3G model but if it is slightly worse than the iPhone 2G battery life, I'd say that it is pretty much the same as with the Diamond.

5. the iPhone camera is 2MP only and can't record videos(without a third party app but quality isn't great) but the resulting pictures are pretty decent for a 2MP camera, especially when there is sufficient ambient light. The Diamond camera has an autofocus and the pictures seem to be sharper and overall better but it also takes longer to take a picture with the Diamond camera.

6. the Diamond rings a little bit louder than the iPhone(even with the ringtone mod), which is also a good thing.

7. for business usage, the Diamond offers a wider range of third party applications right now compared to the iPhone but this could change with the introduction of the iPhone fw 2.0 and the 3G iPhone.

Overall, I'd say that it is difficult to make a decision between both, this is why I'm also getting myself an iPhone 3G too. For business usage, the Diamond may be the better choice right now. For watching videos and listening to music, the iPhone may be the better choice, especially if you have an iTunes account. Unfortunately the iPhone lacks an A2DP profile(not sure about the 3G version but I guess this ain't much different), so if you're not into iTunes and if you want to listen to your music using a wireless headphone, the Diamond is the better choice.

The iPhone works like it should work, there is no hassle using it, switching from GPRS/EDGE to WiFi and back works perfectly(much better than on the Diamond), this is a phone with less features and(currently) less available professional third party software but it is very easy to use and very intuitive, even my kids(4 and 7) love it.

People who aren't too much into ROM updating, iTunes, Windows Mobile/third party apps and such stuff, I also highly recommend looking into the new Samsung F480. This little fellow looks almost like the iPhone, it is smaller(!) and carries a pretty good 5MP camera and a decent touch usability(not as good as the iPhone but usable), incl. 3G/HSDPA, etc. Only bad thing: no WiFi.

If the touch usability is the most important thing to you, the iPhone is the best in this domain, no doubt about it.