ETFs are well established and they have lower fees than mutual funds, however, there are brokerage fees to consider. Also, ETFs can serve as tactical allocation tools for overweighting and underweighting sectors of the market.
SPY is down 32.4% year-to-date, while VTI is down 32.6% year-to-date.
We talk about how you can use ETFs in your portfolio in iMoney: Profitable ETF Strategies for Every Investor.