Very easy.
The thing is... no matter how complicated or hard, you only need to learn ONCE. It's always hard (especially when you switch) when you use SOMETHING NEW, no matter how simple it is.
Let's say you bought a new Digital Camera, surely you see the menu and so on, you wanna "pengsan" like very complicated, but after you "play-around", actually, you will slowly find, it's very simple, heck you may even feel lacking this and that, why got no this option, why got no that option (but when you first touch it, you feel like soo many things).
Even Android maybe complicated and have many features/settings/etc. Once you get used to it, you will feel still feel that, it's incomplete and missing this missing that. But having more things/features, you get to enjoy more.
As for N9 (MeeGo), it's like between iOS and Android, it's simple like iOS(easy to use, little/no customization, etc), yet powerful like Android (little/no restrictions, no need to worry sit in jail, etc), although actually, there is one primary advantage of MeeGo over the rest, the true multi-tasking.....
This is OS wise... which most people don't really bother because most people actually want/bother about apps/games only. So, really depends what is important to you.
To Irfar2397....about the capability of a single core to handle multiple apps....so far i don't have any problem at all....my unit has always have at least 9 running apps at the back and never give me any lagging problem....