Long posts, the ability to embed media, and the simple, granular way to group contacts (friends, family, random people I'm "following" a-la Twitter, integrated live text/voice/video chat, etc.) are all things I prefer about it.
There are definitely negatives but so far the largest one I've found is that it was positioned as an alternative to both Facebook and Twitter but since none of those platforms are built on any open protocol (nor is G+ for that matter), it requires creating and maintaining yet another profile and platform for users. For the vast majority, that's just too much friction and it would require more than a nicer interface and a few features to see any large-scale adoption.
There are definitely negatives but so far the largest one I've found is that it was positioned as an alternative to both Facebook and Twitter but since none of those platforms are built on any open protocol (nor is G+ for that matter), it requires creating and maintaining yet another profile and platform for users. For the vast majority, that's just too much friction and it would require more than a nicer interface and a few features to see any large-scale adoption.