ok I have just received a new n900 and so far so good, though I do miss a few things from the n810...
a) Is there a way to get the n900 to adjust the brightness of the screen automatically based on ambient light? I actually think that the excessive brightness seems to affect my eyesight, and have turned it down to minimum for indoor use. It's a pain having to adjust it manually.
b) How do I get the hardware zooming/volume buttons to perform as I wish? Sometimes I want to zoom in on the screen and the buttons seem to want to adjust the volume

Thanks for your help!

a) It automatically adjusts itself outdoor. I had mine at 3/5, in direct sunlight I can still see the screen perfectly.
b) Depends on the application you use, only one I found you need to zoom is Web and that already has the feature you mentioned which is using the volume key to zoom.

Venomrush,

thanks for your input! I hadn't realised that it actually does adjust the brightness in bright sunlight!! (I had only checked indoors...)
As for the zooming function...You must have very good eyesight!! I find it very hard, if not impossible to read certain fonts sizes. For example I struggle to read the brief desciptions under installable applications. There was also a screen I came across (can't find it at the moment...) which wasn't a web page and was impossible to read.

Maybe I need to invest in some reading glasses, though I don't need any for normal reading. I might have to call them my n900 glasses...
Thanks again for your help!