I made an Ornstein build myself with 24 Str, 30 Dex, and 40 Faith. It's not bad actually. Physical of 142+131, and Lightning of 97+82. I mean...I do still wish the weapon did a tiny bit more damage but if you build the stats around its scalings like that it gets you out some pretty good damage, and the thing is really, really, really long which is a pretty decent advantage. Now that Fog Ring can be locked onto now it must be pretty annoying to fight against. Does damage about on par with the other spears, maybe a little better. I won't say it's the best weapon in the game because of course it's not, but it's pretty fun.
The only thing is making a build around the Dragonslayer sort of requires pretty decent stat-age, so it's kind of meant to be a 120-130 build in my opinion, maybe 100 at the least. Not really meant for lower level stuff, doesn't have the stats to bulk it up. The build itself I'm finding pretty useful overall for other stuff as well when I'm not pretending to be the Dragonslayer. lol I keep Ricard's Rapier as a standby weapon and plan on taking it to +15 and getting enough ears to get Darkmoon Blade to enchant it.