Depends... If you think you'll be able to look at it in 40 years and say, I'm glad I got that, then go for it. If not, don't. BTW, one of my cousins got an armband inked in a few years ago, and he's already wishing he hadn't.
It's all about how you'll look at it later. JMHO
Oh, and as far as placement goes, that would be about ideal. That way, if you want to cover it up a t-shirt will cover most situations - not so easily done if it's on the forearm.
gd