What kills you with Bitcoin timestamping is transaction costs. It's fine for timestamping that one brilliant screenplay, but not timestamping every photo you ever take, every video created by your security system, every file pushed out to your distributed, decentralized backup network, etc. It doesn't open up any cool applications that aren't served by existing, cheap-but-not-free systems.
So with Crypto Stamp, they combine all the hashes for a given day into a single Merkle tree, and just store the root hash in the blockchain once a day. The tradeoff is, for each timestamp you have to store locally the few hundred bytes representing your branch of the Merkle tree. But in exchange, you can timestamp effectively unlimited files for effectively zero real cost. That opens up the kind of wacky game-changing applications that make Bitcoin interesting in the first place.