Don't let One L freak you out! It's worth reading for quasi-fun, but just know that law school isn't a protracted nervous breakdown unless you're someone really insistent on turning it into a protracted nervous breakdown.
And this is just my $0.02, but I would recommend not getting hung up on reading supplements before school starts. I'm all about E&Es -- I think they're great for many classes, and where I've used an outside aid, they're the only series I've turned to. But you won't understand how to use them or what parts to cover until you're in the thick of first semester. Plus, your professor may cover as little as half of what's in an E&E or may cover topics differently. At the best, you've lost some summer hours reading material you won't be using and/or won't retain until December, and at the worst, you might get overloaded and confused in a way which persists into the semester.
That's strictly my opinion, and I know the anticipation is *crazy* and everybody has to decide their study methods for themselves. But I can promise that it's very possible to start Orientation week with very little knowledge of law school, let alone "the law," and still do well. If you've got free time available 0L summer, something more relaxing may actually be a better investment in your future.