Hi!

I have my n900 since 2010 and I still use it as my daily phone.
I do not know what an "average user" needs nowadays and I do not really know what Android is capable of because I do not have any Android phone. My wife has...

First of all - as said earlier - the stock browser experience sucks... I have opera mobile installed and that is enough most of the time for my needs. If not then I use midori - I have kali linux chroot with i3 window manager and midori is quite good on it...
Youtube: with cutetube2 I do not have restriction so it is far enough for me; I'm able to watch any video but you have to set it up properly (search for the threads...).
Development: I learned python on the phone itself and wrote some apps, scripts - I find it quite useful. But: you have to keep is mind that the stock python is 2.5 and I would not recommend to update 2.7 or 3 because maybe some compatibility issue can occur or simply there is no module for that... On kali image there is python 2.7... I did not try Jupyter though...
I have a "development maemo image" on my phone so I can write (learn) C code than build it or simply build any app if it is possible (last time I built sqlcipher with checkinstall). It is useful but of course has limitations...

I connected it to my TV (with scart adapter, hahaha) in the past to watch movies but nowadays I don't. But you can do that of course but be avare of the resolution...

So all in all for me it is good and I would not cahnge it to any Android phone. Would I buy one...? I do not know since I would not know any linux stuff without is
Keep in mind that if you want *any* android app/experience then n900 is not your phone because there is no such apps for it (as far as I know).