Yesterday I started writing up a quick review of my new phone/tablet, a Nokia N900. Unfortunately it has since broken down by what appears to be a hardware issue. It does still work to a certain degree, as the leds flash and I can access it as a USB mass-storage device, but the screen hasn't shown anything since I woke up this morning. The timing could not have been worse, as I'm currently abroad and having a phone (as well as a GPS) would be useful, especially considering the ash cloud situation in Iceland.
Update: 4 weeks after dropping my phone off at the Nokia care center I have received a new N900; they weren't able to tell me what was wrong with the old one.
Anyway, my thoughts about the N900. Please note that I haven't used a lot of other smartphones, so I can't really compare this with Android phones or iPhones.
The integration between the different components of the phone is really well done. Nokia has invested heavily in Telepathy, which is used for all voice and text messaging, and it shows. Skype and regular telephony are very nicely integrated with telepathy, albeit through proprietary daemons. There is one global status for all protocols. Skype and SIP conferencing work well.
The address book is another thing that is very nicely integrated with the rest of the device. It combines IM addresses, phone numbers, email addresses and other information for a contact and there are third party applications that can help keep that information up to date.
Both the Ovi maps app and its data are free, and it's possible to copy the maps onto the device so you don't need to stream them all from the internet when you're abroad. It's pretty quick compared to e.g. a Garmin GPS, but lacks features. It can't load GPX files, can't show points of interest, store tracks, etc.
The music player is neat and automatically indexes all audio and video files that are copied onto the device. The camera and photo manager work well, and are reasonably snappy.
The web browser displays all pages I've accessed so far without rendering issues, including flash.
There are quite a lot of neat third-party free software applications available - eCoach, Hermes, grr, mBarcode, Mauku, tubes, tuner, fahrplan.
Maemo is Linux-based and it has a lot of similarities to your average Debian-derived distribution. Despite that, it contains a lot of proprietary software. In particular, the Skype and POT plugins for telepathy, the address book and things like Ovi Maps are proprietary. This means it's impossible for me to fix little annoyances (see below) in these packages, but more importantly, it's impossible for others to fix these little annoyances or port these apps to the desktop and other devices (where there's an even larger pool of potential bug fixers).
The GPS doesn't work very well. This might be due to the fact that the hardware is substandard, but I suspect it has got more to do with the fact that if it does not find a signal within 30 seconds it will switch itself off. I assume this is to save energy, but this behaviour can not be switched off anywhere. A workaround is to close and reopen Ovi Maps every 15 seconds or so, but that's pretty annoying. I'm sure somebody with access to the source (I don't!) can fix it.
I'm sure the calendaring app is nice, but it lacks support for synchronization with Google calendar, which makes it unusable for me.
The standard email client does work, but it doesn't scale well. It will lock up at times while trying to index mailboxes. I've tried using claws mail for a while, but its interface is just too cumbersome - in general, but in particular on such a small screen.
The battery lifetime sucks. If I'm lucky I can make it through a single day with a fully charged battery, with only mild usage. The form factor is also still a minor issue for me, but I doubt that bit can be fixed in software.
Overall I'm pretty happy with the N900, although I'm not sure if I would pick it over an Android phone again.