It's hardly the winner, one of Cowon's players can reach 50+ hours (with a touch screen, granted it's only 2.5" IIRC). It's very respectable though... And supposedly better than the 1g, though I haven't tested that claim myself.
As for 1g vs 2g, besides the battery... The speaker is hardly much of an upside, it sounds really tiny and way more muted with some apps than others. My videos in particular can hardly be heard over the speaker, I dunno if it's an encoding problem, they sound fine over headphones... It's passable for showing someone a song preview on iTunes or a Youtube video though.
You can barely hear app sounds (like say, a game's sounds) if it's noisy around though, like say... Think crowded restaurant. The volume buttons on the other hand are a much bigger deal, it's certainly nice to have those. It's not hard to get at the volume slider (double clicking Home at any point brings it up along with some playback controls), but it's still easier to adjust w/the buttons.
It's definitely not very useful as an alarm clock unless you're a light sleeper, heh.
The Nike+ and mic support is more of a personal thing, some people won't care much for either, some people will be all over it. The mic has a few uses, such as voice annotations, or doing VoIP calls... And all you need is a $10 mic adapter w/a 3.5mm jack for your own headphones (no need to buy apple's overpriced/crappy headphones w/integrated mic).