Nebulas introduces a blockchain-based ranking algorithm called "Nebulas Rank" (or "NR.") It's inspired by PageRank, so a lot of people have settled on the notion that NAS will be "the Google of blockchains."

That is indeed one possible application of NR, but Nebulas aims to do far more. It will be a fully functional smart contracts platform that uses NR to reward DApp developers for successful projects..

From the white paper:

In order to create a good community for Nebulas, we propose the Developer Incentive Protocol (DIP) for smart contract developers and express our appreciation to outstanding smart contract developers who contribute to Nebulas by rewarding them NAS. [...] As a kind of universal value criteria of accounts, NR can be used to assess high-value accounts. The design of DIP combines NR and the common WAU (weekly active users) concept, the total WAU value measure is used to evaluate the value measure of the smart contract.

Furthermore, it will be fully compatible with smart contracts written for Ethereum:

Since Ethereum is a successful public blockchain platform with an ecosystem of massive scale, Nebulas hopes to learn from Ethereum’s excellent design, and make smart contract fully compatible with it, so that Ethereum-based applications can run on Nebulas with zero migration cost.

This is huge. It means that smart contract developers no longer have to rely on ICO funding. They can take DApps they've already written for Ethereum, deploy them on Nebulas, and be continuously compensated in a way that is proportional to the success of their work.

It also means that Nebulas will inevitably host a steady supply of high-quality DApps. If you write a DApp for Ethereum or NEO, and you can make some extra money by also deploying it on NAS, why wouldn't you do that?

Finally, the team is world-class, and includes two NEO co-founders. Hitters Xu has been a major player in the Chinese crypto space since the early days of Bitcoin. He's also listed right alongside Da Hongfei as an advisor to Loopring. It's highly unlikely that a project with Hitters at the helm will fail to be massively successful.