Yeah, just one. And frankly, it didn't look bad at all. Gave him a creepier, more menacing and tribal warrior kind of appearance. Klingon appearances have been all over the board since "Errand of Mercy" back in 1967 and this one isn't really any more radical than others seen in the franchise since the development of vastly more sophisticated makeup techniques for ST:TMP.
I still think the TMP Klingons look more intimidating and nasty. I'm just glad these didn't rehash the "long-haired Viking biker gang" look that became the run of the mill, default makeup choice when depicting Klingons in the 24th century series and films. They were cool (especially warriors like General Martok), but it got pretty stale. The STID Klingons took the best of the updated makeup design and added a few intimidating twists, and it was a good choice.
If you're not going to tackle the Augment mutation virus afflicting the Empire around this time in history and you feel the need to show a Klingon with head ridges, might as well make him look as badass and cool as possible.