Almost every bridge asks you to trust a group of entities to attest that something happened on another chain. IBC does not. Each chain runs a light client of the counterparty chain and verifies consensus proofs directly, which means the security of a transfer reduces to the security of the two chains involved.
Why that is categorically different
The multi-billion-dollar bridge losses in this sector — Ronin, Wormhole, Harmony, Nomad — all involved compromising a validator set, a signature check or a key. IBC has no such component. There is no set of signers, no multisig, no attestation service. The failure mode is a chain's own consensus failing, which is a different and much higher bar.
The limits
IBC works between chains that can run light clients of each other, which in practice means Cosmos-SDK chains and a growing set of adapted implementations. Connecting to Ethereum or Solana requires additional machinery that reintroduces some trust. And a connection is only as strong as the weaker chain's consensus — IBC to a chain with three validators inherits that weakness.
Cost and practice
Gas only. Transfers typically complete in seconds to a minute depending on block times, and wallets such as Keplr handle routing so users rarely see the mechanics.
Who should use it
Everyone operating within Cosmos, which is where it works. Its wider significance is as the reference standard other cross-chain designs are measured against.