It would be pretty close, since there is no pending legislation to change tax rates, and the tax bracket boundaries have only shifted slightly.
However, keep in mind that your marginal tax rate is often more useful that your effective tax rate. Your marginal rate comes into play when you make a financial decision that affects your taxable income, e.g. contribute to a tax-deferred retirement account, an educational savings plan, or earn extra income.
Suppose your effective tax rate is 12% (meaning that your tax bill was 12% of your gross income), but your marginal tax rate is 25% (meaning that you are in the 25% tax bracket). If you contribute $1,000 to an IRA, your tax savings would be $250, not $120.
I am trying to figure out what my 2017 effective rate will be based on my 2016 effective rate so that I can adjust my withholding accordingly to make my amount owed/refunded from the IRS as close to 0 as possible.
In that case, I typically look at the entire estimated tax for the year, not necessarily as a percentage (although the math isn't much different). I then look at my withholdings and extrapolate that our for the year to see if I need to increase or reduce my allowances.