I had one and returned it.
Android just is not a pleasant experience IMO. The silliness of a home button is laughable. Try using Meego Harmattan on the Nokia N9 and you'll never be able to go back. I really, really wanted to like the N4 but I couldn't. The slickness of going in and out of apps and having your feed built in to the OS itself is too much to pass up on.
BB is about the closest you can get to it right now (before Jolla comes out.) I've used it for about 15 mins in the store (admittedly a short time) but felt right at home with the OS. The multitasking is superb, the peek/hub feature is brilliant, and the apps are ok (needs more or at least more Android ports.)
A little more polish and BB10 would be the go to OS in the market if it could break the duopoly of Android/ios.
JMHO but this phone is definitely worth checking out if you like to be able to move in and out without delay.
that's what everybody said about webos, symbian, and even meego.