I'm not going to claim that they're OP or anything like that, because they're not. I know there's ways to counter them and all that.
That said... if I wanted to play hide and seek, I would have had children. Instead, I decided to get addicted to plastic crack and live out sci-fi fantasies in the grim darkness of the far future where there is only war.
I get the point of Dark Eldar. Their tactics are very much in line with the story behind them, they reward clever strategy, and I understand the niche of the "stealth fleet." I just wish fighting them wasn't so infuriating. At this point I just immediately capitulate when I'm up against them, simply because I want to move on to a match that might actually have some semblance of fun.