A yield aggregator is a manager. It takes your deposit, allocates it to strategies you did not choose, and charges for the service. The only meaningful question is whether you can find out what it is doing, and Yearn answers that better than anyone in DeFi.
Strategy transparency
Each vault publishes its strategies, the protocols they touch, the risk factors involved and a risk score with the reasoning behind it. That means a depositor can determine, before depositing, that a vault is farming a specific lending market and is therefore exposed to that market's collateral policy. Most competitors describe strategy in a sentence of marketing.
Fees
Typically 2% management and 10–20% performance, which is the heaviest in the category — Beefy charges around 4.5% of harvests and Convex around 17% of rewards with no management fee. Yearn's argument is that active strategy management and security review cost money. Whether that premium is worth paying depends on whether the strategies actually outperform, which varies by vault.
Security record
A v1 DAI vault was exploited in 2021 for around $11m through a manipulated Curve pool, and a smaller yETH pool bug occurred in 2023. Both were disclosed thoroughly and partially recovered. Five years of production across many vaults with two incidents of that size is a reasonable record for a protocol composing this many external dependencies.
Who should use it
Depositors who want to know exactly what their capital is doing and will read the strategy documentation. Cost-sensitive users farming simple positions should use Beefy or hold the underlying position directly.