No, it's not too long at all. For APS-C, many of us consider around 75-85mm to be optimum, but even that is no fast and hard rule for portraiture.
Before I moved to full frame, I generally carried three lenses for an outdoor portrait shoot. They would be a 35 f/2, an 85 f/1.4 and a 300 f/2.8. In a home, I'd drop the 300mm, of course.
With full frame, I've kept all three and added a 105 f/2.5 to the mix.
One thing casual portrait photographers fail in is getting in really tight. Most of the space around the subject is a waste and doesn't contribute. Again, thats not hard and fast either, but a good thing to consider.
The 50mm will be a little wide, actually as what might be considered the perfect portraiture lens or a one lens fix, but it will do quite well if you're willing to move right in. For a head shot, you might find yourself in so close as to be a little uncomfortable for the subject. With my 35 f/2, I often find myself only inches away. It distorts features a little but gives depth and space.
Here's my grand nephew shot first up tight with a 35mm and then back with an 85. I'm not the best photographer, but this is to show the difference in perspective with different focal lengths, not to show great portraiture. With the first, my 35mm was almost touching his elbow.
Both shot with a Nikon D300 (APS-C) and both at aperture.
35 f/2 at 1/80 and f/2
85 f/1.4 at 1/200 and f/1.4
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Cheers, Craig