Symbian can indeed do many of the functions Android does, BUT does it do them as well as Android does them? NO!
I have both an SE X10 and Nokia N8 here. Got the N8 last week but guess what im using to write this post, and on a daily basis? Yep, the X10.
Symbia^3 has this incomplete Beta feeling to it:
-Extremely poor notification system, 3rd party apps dont even take advantage of it.
-Widgets, they are anywhere other than the Main homescreen e.g if i have a news or email widget in the 2nd or 3rd screen it, that widget sits there and doesnt update itself until i go to that screen, updating it may take 5-10mins which completely nullifys the whole dam point of widgets, in the Android i have widgets in every homescreen, i can set each widget to update at its own frequency regardless of which homescreen is the main. Widgets are just so poorly implemented its sad!
-Email, i have set up a Gmail account on both my Android and S3, both get push email, my X10 gets my emails sometimes 30-40mins before the N8 does, sometimes it never arrives on the N8 if my Mail widget is in the 2nd or 3rd homescreen.
-Social Networking. SHOCKING! The whole Social app's idea is genius but so awfuly implemented, its actualy a joke, it depends on the Web browser too much especialy for Twitter, the Android FB and Twitter apps whipe the floor with it.
Web browser- Still no option to open another tab, you have to go to a website then click a link that should open in another tab, totaly ridiculous, not to mention how slow and unstable it gets due to just one large site, in Android i can go bonkers, open multiple windows with multiple large sites and still browse so smoothly with no stability issues or slowdowns. I tried using Opera Mobile on the N8 but all it did was to eat up resources like crazy, im talking upwards of 50mb RAM, it brought me dangerously close to running out of RAM.
These are but a few things that ive had issues with, its not about flashy UI, its about things working PROPERLY and they just dont in Symbian^3, the hardware is decent, but the software is just not upto par, it ruins the experience, i was rather letdown.
Migo is right, in terms of the look and feel of S3 its not that different from S60v5, there are nice tweaks here and there e.g. long press, but otherwise still quite a poor effort, IMO.
Battery life is great in the N8, thanks to the fact that im hardly using it, and when i do i get frustrated.
EDIT:
So as i said, yes, Symbian can do many things Android can, but Android does them far better and is a lot more reliable. Symbian can promise all the updates they want , but Android already works very well, and is going to get far better next year, its not like Google are just sitting back.