Chris Paul and Deron Williams are half a step above him, they are both complete players. Right now, Rondo is in Nash and Rose neighbourhood. Nash lacks defense, but is a great distributor and shooter. Rondo lacks shooting ability, but is a great distributor and defender. Rose lacks defense and is not a good distributor, but he's a good shooter and a great slasher, and is like a little Lebron, so he's already a top 5 PG.
Below them, there's Westbrook, who could end being a top 3 PG if he keeps improving, Jason Kidd due to age, and Tony Parker.
Looking ahead, I wouldn't complain about having a top 3 PG. Only Paul and Williams could be considered upgrades, but even then you'd have to see if chemistry works out well.
I'm happy with Rondo as long as he practices with Ray Ray his FTs and jumpshooting, he's probably the best guard in a Celtics uniform since DJ. Furthermore, I still see him as these days Cousy, waiting for our next Bill Russell in order to dominate the league in a sixties way.
Go Celtics!!!