An early-age IOTA investor has claimed that the project is centralized and is exposed to a single point of failure.
Limo, who runs an IOTA-specific blog called TangleBlog.com, identified issues related to how IOTA’s data structure operates. The project uses Tangle, a Directed Acyclic Graph, known as a DAG, whose primary purpose is to hold transactions. Unlike a Proof of Work (PoW) blockchain, which enables an entire network to confirm blocks carrying transactions, IOTA’s Tangle does the same via appointing two previous transactions to establish the new transaction. Here is a brief illustration: