Thought I should update how I'm doing with the N800, after a couple of months, especially as it now has a rival for my attention
Yes I finally went out and bought an iPhone when my old KJam conked out completely, and the SE Xperia's delivery date kept on being pushed back.
Once I got it (About 3 weeks ago) I do admit that I did ignore the N800 for a while, as I tried to get used to the in's and out's of the iPhone, especially as almost everything has to be managed through iTunes, and I've personally never used an iPod for a longer time then it would take to Load something for a family member.
First the Comparison
Browser - Have to admit that except for a few sites, Mobile Safari is quiet a bit better then the N800's browser being faster and easier to use, and the ability to sync bookmarks is a joy (Especially when you have over 2000 of them). The Pinch and Zoom works really well, and with many major portals having iPhone specific portals the experience is nice.
Having said that, I have to say that Safari at times is incredibly unstable, often crashing constantly. The update to 2.2 appears to have stabilised it somewhat but will have to see.
One of the Major pains is that the iPhone doesn't support Flash, and it can be a pain especially with sites with streaming content, both audio and video.
Also you can't save any files except photos which is a pain.
Email - the iPhone is incredible good at this, especially at handling multiple accounts, which I found to be pain on the N800.
Organiser - The N800's archiles heel. The iPhone's Exchange sync, though missing Tasks and Notes handles Contacts, calender and Email really well, and keeps them well in sync.
Media - Its a bit of mixed bag really. While the iPod facility is good and easy to use, it is limited in some ways and I find I miss Canola.
First I miss the Multiple format support from Canola, which could handle most codecs for audio and video. The iPhone is limited to mp3, aac, m4a and MP4 and m4v for video and that too no more then 640x480.
While the N800 can struggle to ply higher resolutions, it at least allow you to load what you want. I've had to convert a lot of my Videos to MP4 to MP4 for the iPhone, with the advantage that I can also easily play them on the N800.
What I really miss is folder navigation in Music, as the iPhone sorts only based on Metadata and a lot of my library has incomplete or incorrect metadata, so its a bit of pain to have to edit all the metadata before loading. While its good in the Long run, its still a bit of a pain.
Podcasts - I listen to and watch a lot of Podcasts so this is really important to me. One of the Major PITA's of iTunes is that it will not allow you to add files to certain categories like Podcasts and TV Shows directly. You can only add to those categorises if you download it through iTunes.
So That meant that I could not use my down loader of choice Miro to download and organise my library, as it add too many steps to the process. So I ended up using iTunes to manage them and while it works, it does bring something else to the forefront of my mind.
iTunes is a SYSTEM HOG. I've known this in the past, but its really hit me the last few weeks as I usually have in running in the background, downloading and it really hits system performance, not to mention the lack of some critical features.
Documents - the N800 is miles better, being much easier to get stuff on and off. With the way apple's got the iPhone locked down, the only way to get documents onto the iPhone is through the Wifi, which can be very slow, especially as you can't run it in the background on the phone.
Reading - FBReader and Evince ar still great, and coming back to them after a few days of using just the iPhone really makes you appreciate them.
Having said that, Stanza and the eReader app are great for reading on the iPhone, but the hard part is getting your own content onto them.
So i've currently got a large part of my library loaded on the n800 while I use the iPhone to read the newly purchased stuff, as I've recently been buying in eReader, and then converting it to Mobi for my Cybook.
Comics - Definitely sticking to the N800 for this as Evince is great for reading CBR and CBZ file, the format in which I have most of my comics. While there is a comic reading app for the iPhone, it still requires you to convert the files before loading it slowly over Wifi, I couldn't justify paying for it. Having said that you can read Jpg's and PDF's in the Files and Air Share app's, though they do choke on larger PDF's.
So what has this meant?
Well, it has meant that I no longer use the N800 as my out and about Music player and Net Access appliance as the iPhone handles it reasonably well.
This doesn't not however mean that the N800 has been relegated to a drawer as I use it constantly at home for Streaming Music and Video, as well as a Skype appliance. As the iPhone can't handle WMV streams, and some of the stations I watch and listen to only use that, the N800 is a lifesaver.
I'm also using the N800 for reading comics and referring to PDF's as it is easier to handle and manage the media on it.
In the end both have their strong points and I'm enjoying using both.
The main problem I run into when switching between them is the different ways in which the screens work and it takes a few momennts to get used to the difference each time