About time I ventured to this thread considering how much I loved playing a female qunari. First benefit: We got to see for the first, and so far only time, what female qunari look like if and only if you play as one.
You really notice just how large and muscular like a female wrestler they are when you've played as an elf for almost 100 hours and then load up an old female qunari save and are taken aback by the contrast. When playing as Addar I didn't really see just how busty she was until switching from an emaciated elf. And their height displays that authority that comes with inquisitor, although logically it should be irrelevant. My favorite part was when she lifts the sword after becoming Inquisitor and entering Skyhold in front of her advisors; much more powerful than other races.
Fortunately qunari also have magical ability. That would be a deal-breaker for me because I almost always play as a mage. What's scarier than six and a half foot tall horned qunari; one that's a mage.
I also loved instead of helmets (besides Dread for Iron Bull) they used face-paint. Face-paint looks great on a qunari. I normally hate helmets and appreciated the option to hide them. In past games I just wouldn't wear one. When playing a qunari though I don't hide them. This gives a ever-changing look to Addar including in the cut-scenes as the face-paint remains.
Negatives of playing as Addar? Qunari have always been kind of "there" in the background in Dragon Age; Tal-Vashok even more so. They don't have much of a role besides being the really tall, horned, badass looking race from far away. We know so little about the qunari in comparison to the others. What is the race even actually called? Qunari is used both for those following the qun and the race.
Humans are obviously the most significant race followed by elves. Elves have much of the "once upon a time we were blah blah" intrigue as well as the "one day we will rise again" aspect which was exasperated by Flemeth and Solas' apparent goals of recapturing the old elven glory. Dwarves are also more familiar than qunari but don't have the same significance as humans/elves.
Other negatives? Why would anyone pass up playing as a badass qunari for a scrawny elf or a plain human? The romances obviously. Two of my favorites, Cullen and Solas, are sadly blocked off from qunari. I can understand why. Solas is all about elven glory and Cullen is picky. He's handsome and has appeared largely uninterested in courtship so he'd probably be less inclined to romancing someone six inches taller than him who has horns and grey skin.
My favorite romance for a female qunari was Sera who not only is a fulfilling relationship but happens to woof for qunari women; adding intrigue. Honestly Sera hit the jackpot by managing to satisfy her fetish by bedding a qunari who happens to be the Herald of Andraste. I'd recommend this romance if you're ok with lesbian relationships and can actually stand Sera.
Last but not least, there's no race better for punching Solas and Dorian than a giant qunari.