...be warned - you CAN brick your fone if you interfere with it or the cable when the firmware is downloading/updating, and you WILL invalidate your warranty with your service provider (and possibly Nokia) if you change your product code. Having said that, i went ahead and did it anyway, and my menus are a lot more snappy now - its a shame the new firmware (v3.0649.0.0.1) didnt fix my slow camera problem... Ah well, heres hoping the next firmware upgrade will address that issue - ARE YOU LISTENING NOKIA?
Before you decide to use NSS to change your product code, make sure you do your research first - do NOT attempt it unless you are 100% (well 75%) confident you understand what you are doing.

To the poster having probs with text messages taking ages to send - you have two options:
1. Visit the Nokia site and download the sms accelerator update
2. Update your phone to the latest firmware at the Nokia site
Regarding this - i was unable to update my firmware because O2 havent approved any later firmware than i was using, so although Nokia have released several bugfixes, im apparently not allowed to have them! There is a way round this, by using Nemesis Service Suite to change your handsets product code, to a generic brand-free one, not restricted to a certain firmware. I recommend doing this - i managed it, and im no technical wizard. However....

Nice phone - but definitely flawed. Camera takes really nice pictures during the day but forget night shots as the flash is poor.
My last phone was a mid range 6230 which served me well for 2yrs but the time came for an upgrade so i paid O2 £100 for the N73. Great features, some of which i will not use, but as spelled out by many others, the fiddly joystick, small keypad and slow laggy software hold this phone back. Ive not had the phone crash on me but i have had it tell me "memory low, close some applications" when trying to zoom in on previously taken photos. The N73's flash memory is sadly lacking, and the fact that some applications do not close but instead continue to run in the background mean you can sometimes run into problems like i have just described.
There is loads of handy software such as Tomtom Navigator etc that can be downloaded (for free if you know where to look) and it is really nice having a tiny pc wherever you go. However the attention to detail just isnt there - omissions such as a text message counter (essential, once you get used to it on another phone) just arent acceptable.
The gallery for viewing photos is poorly executed as well - it just pulls up any image on the phone or memory card and presents them in the order they were saved - meaning i am risking showing ahem, risque shall we say, pictures of my bird to my mates accidentally when trying to locate another photo! And they are all mixed in with images used by Tomtom, such as road signs - the gallery is a joke. There are workarounds using different software that can be downloaded free, i mean PURCHASED - but thats not the point, it shouldve been done right in the first place.
For all those criticising the menu being too complicated - get in the real world, its a computer not a toaster, if you cant handle it then get a more basic phone, In any case, the menu can be customised and everything moved wherever you want it, so if you spend a few minutes then you can have all the things you use regularly easily to hand anyway.
The camera is SLOW, takes 6 seconds on my phone from opening the shutter to getting ot a state where you can actually take a picture - hardly any use for those spur of the moment shots. And the pictures, although very pretty, are too colour saturated and not true to life. Your decision if that makes good photos or not - i think it does. Having said that, im only a novice with the camera and find it is slow to take pictures as well - youre looking at 2 or 3 second from when you push the button to when the picture is actually taken (unless using sports mode) - this means sometimes poses go out the window and you end up with someone who has moved in the middle of the shot because the flash has gone off but the shutter hasnt closed.
The web browser is pretty good but id advise downloading Opera Mini for free, as it saves your download bill by going through Opera servers which strip out all the rubbish you dont need and compressing web pages to a smaller size - do some research on google about this, its worth it.
The body seems cheaply constructed and "creaky" but thats no biggie to me.
Speaker phone is next to useless - and call volume not very loud when using pressed to your ear.
It sounds like im really slagging the N73 off, but i do actually like my phone - it just couldve been so much better. At the end of the day its on a 12mth contract so hopefully Nokia will have sorted out the issues it has when they release their next smartphone and im ready to upgrade again.
Oh and get a latex screen protector off Ebay for £3 - means you dont worry about scratching the huge screen any more - this will also help the resale value when you upgrade and get rid of it. At the end of the day ill easily get £100 if not more for it next year, so really the phone wont have cost me anything.
I dont know if the Sony equivalent is any better, and i wont ever touch another Samsung - admittedly i am a Nokia fan, for the ease of use, so make what you will of what ive written!