Multitasking works well.
Eldar used the phone the Android way, i.e. never closed any app. Of course after some time memory gets full and the device starts to swap and lag.
On average days I have 9 - 12 apps open at a time and experience no problems at all with multitasking. 9 is a good number because you can see them all at a time in the task switcher without scrolling.