Spooky timing....
I've had my Warmoth neck for 2 years now, and in that time have used it every day and on hundreds of gigs. It came with jumbo stainless frets and a vintage tint satin finish. In all this time, I've never done anything to the frets. I literally took it out the box and screwed it onto the body. Until yesterday......
Now, I have to be honest, the fret work by Warmoth is non-existent. Yesterday I took the guitar to my tech and finally agreed to have something done about the 'out-of-the-box' fret work. The frets are exactly how you describe: very 'straight-up' at the edges. The other thing Warmoth do is to apply the neck finish after the frets, so when you receive a finished neck it will have the finish covering them.
However, take into account that it can't have been THAT bad, or I'd never have made it through the past 2 years with what is, by all accounts, an incredibly good neck (that's the important bit here). So yes, they're clearly useable straight out of the box, but if you want the best you'll have to get some work done on it. It was only after spending last weekend playing some Suhr guitars that I realised quite how badly my strat needed some fret work!!
Hope that helps. Don't be put off, the necks are brilliant (as are the bodies), but don't be as lazy as me....get some fret work done asap :-)
Cheers
Jordan.