Well it depends on who you are, personally I really wanted to get a SGS2 and want to get a GN now but I just couldn't stand carrying those around all the time.
You'll get used to it. The display size is getting standard soon.
Doesn't help that both the SGS2 and GN feel cheap in the hand as well, not major but for the price you pay you would expect it to feel premium.
They don't feel cheap at all. The Galaxy S2 is more resistant than the 4S when both fall to the ground.
Android and bada (both used by Samsung) are the only two operating systems gaining market share at the moment. Even more, Samsung has overtaken Apple concering worldwide smartphone sellings in the last few months.