I made my first hat on straight needles...it was the first thing I ever had to do any shaping on so I didn't want to deal with circs for the first time on that hat. It came out well, although my seaming looks a little crooked. But, it's warm and it hasn't come apart yet, so I say it's a success!
If you use straights, make sure you use the longer ones so all of the stitches for the hat fit on the needles.