About half of this double cd set was already familiar to me - mostly the middle half - but I'm on enough of a Neil Young kick at the moment to be happy to repeat-listen to the discs all the way through notwithstanding.
From what I can gather (from the liner notes), the early songs are a mix of tracks written and recorded with and around the margins of Buffalo Springfield and CSNY and a few that Young wrote and laid down entirely on his own. It may just be the perspective from which I'm looking at them (ie, a retrospective one, comparing them to what came after), but they seem a bit unformed, the ideas and sound rather inchoate; they're mostly fairly nice (though I'm not getting "Broken Arrow" at all), but I have a feeling I'd give them fairly short shrift outside the context of a Neil Young collection. Then come all the songs that I know, interspersed with a few others; of those that I didn't already know, I particularly like "Winterlong" (Young's take on 60s girl group pop, complete with 'sha la la las', echo-commenting backing vocals and fade-out ending!), "Deep Forbidden Lake" (though its melody reminds me of that Bee Gees song "Words") and "Campaigner".
A provisional 'top 10 Neil Young songs' list (not limited to those on Decade), rendered particularly provisional by my not having explored large parts of his back catalogue:
1. Only Love Can Break Your Heart
2. Revolution Blues
3. Cowgirl In The Sand
4. Cortez The Killer
5. Helpless
6. The Needle And The Damage Done
7. On The Beach
8. Southern Man
9. After The Gold Rush
10. See The Sky About To Rain
Strikes me as quite a wimpy/soppy list, but then we don't listen to Neil to be macho, do we?