From a consumer standpoint:
There's the fact that the ETF requires a brokerage account and you would be charged commissions on trades. A Vanguard brokerage account will let you trade them for free but if you've got <$50,000 in assets with them it's a $20 annual fee. (Mutual fund annual fees are waived if you have electronic-only statements.)
There's the fact that ETFs must be bought and sold in units; you can't just trade a random dollar amount, it has to be greater than and divisible by the individual share price.
Some funds that have ETF equivalents can be converted directly into ETFs.
That's all I got but there's probably more. There is also some question of hidden trading fees on mutual funds and whether these are allowed or not in ETFs.
