I've never loved Nirvana's "Unplugged" as much as most fans do, mainly because I love their plugged in sound and think Kurt's songwriting, singing and guitar playing are better served in an electric format, whereas the unplugged setting actually exposes his limitations in those areas, especially as a singer. But the intimacy, intensity and nostalgic attachment (clearly remember seeing it when it first came out shortly after he died- 'About A Girl" and "All Apologies" in particular were in heavy rotation on MTV).
"Pocketwatch" is hit or miss like you say but there's some good noisy shit on there and yeah, the debut is closer to that one than the stuff that came later in a lot of ways.
Glad you're coming around to "Last Splash"- I truly think it's solid all the way through, one of the better albums of the 90's. And though I was initially pretty lukewarm on "Pod" due to the demo like nature and Albini's non-production, the uniqueness of the songs have made it grow on me, even if I still prefer the follow up. Recent reunion album "All Nerve" is also really good.