It's pretty much a meaningless question. They both do different things, and where their features intersect one is better in some ways and worse in others. "Apples" and oranges, y'know.

Asking if iPhone is "better" has so many variables, you're guaranteed a subjective response. You'll do better to ask about specific features that are important to you.

I suggest that you look at some of the many youtube videos demonstrating N900 features. Those will give you a good idea of the UI, and the device's size and responsiveness.

Thanks everyone for their comments =) It seems i have to wait before buying. I dont care about MMS, i dont use it. But video calling is much more important.

dmj726, is usb host mode really important and is it comes with any other device?

OK, i understood its meaningless to compare with iPhone =) So whats important for me:

1. Being free and hackable. I think N900 already won.
2. Lots of Applications and Games. I'm not sure about this.
3. Supporting standard features for a high-end product. (3G, MMS, GSM, Camera etc.)

On current firmware, no, on future firmware, maybe. MMS is old tech. Why would you want to use 5meg pixel cam and 3G connection to send a low quality image?

Yes, that's what the secondary camera is for.

Can't comment on this, N900 is a geek phone, not meant for mass market. If you want an easy to use phone, get an iphone for its limited features.

Hardware is absolutely superb in any ways, people only moan for the software, not the hardware. Although for me, the camera can be better, 5meg is consider old tech for me.

USB host mode would allow you to plug flash drives, usb keyboards and mice, etc into the microUSB port on the n900. Right now the only way one would be able to do this is through bluetooth. I suspect that it's a minor use case for 95% of people.
1. n900 is far more free and hackable than iphone...it's not even a fair contest there.
2. This iphone has tens of thousands of apps, compared to maemo's hundreds. The iphone has many more games as well. However, you have to pay for many of those, and Apple does restrict what you can put on there unless you want to jailbreak it. In the end it mostly matters if it has the applications *you want*.
3. The n900 has far beefier hardware, better camera, etc. It doesn't have all the features that say the n97 has for phone calls (mms, voice dialing). Video calling should be coming soon. I would look at it as a set of trade offs. The n900 won't have *every* feature you could want, but it makes up for it in other areas, like the web browser, the keyboard, the tv out, hackability, so try to figure out if the n900's benefits outweigh the few niggling disadvantages

3)

N900 is not a smartphone, it is a mobile computer with some phone functionality.

This linked post is my answer to your third question:

http://talk.maemo.org/showthread.php?t=35058

Hell no, i dont want an "easy-to-use" device, in fact, If I buy N900, It'll b/c of Linux and free software.

For host mode, It doesnt looks like an important problem, I'm using N96 and i didnt even noticed about it.

But I found sth about video calling at Nokia Discussions, they said, N900 uses 3G as only DATA mode, not IP-or vice versa- and cause of this, its not possible to make video calls with N900. I'm not sure about if its true or not.

Comparing the N900 with the iPhone is like comparing a sailboat with a train. They are two completely different devices that are geared towards two completely different type of users. If you are even remotely interested in how it stacks up against the iPhone I suggest you consider buying one or one of the many iPhone competitors.

It is very important you are aware of what the N900 is and what it is not. Its not a full featured phone. Its a full featured mobile computer with phone functionalities. It has some serious software limitations at the moment and only the future knows how Maemo and the N900 will turn out!

2) You can make video calls over IP using Google Talk.
4) No MMS, no at&t 3G, no digital compass, no voice dialing

Its a HUGE disadvantage not supporting video calls over 3G. I'm really curious-and worried- about if its possible in the future or if its hardware problem.