The kits are ok for the money, from what i've seen. The best part is that it lets you use the longer, better shocks. It doesn't give you all the extra leverage and bump steer of wheel spacers either. And if you would happen to annhilate one of your a-arms on a rock or something, stock ones are cheap as dirt on ebay.
Now, here's what I don't like about them.
-They flat-out look ugly and rigged up
-you still have the short stock suspension travel, vs longer travel with aftermarket arms,
-ball joints on stock a-arms aren't replacable, the whole arm has to be replaced if a joint wears out or breaks.
-All those thick steel brackets add a signifigant amount of weight to the front end.
-They don't come with longer tie rods, they come with a cheap little tie rod extender. Very weak, and I don't think it's even safe. I wouldn't even ride with the extender they give, i'd buy longer rods.
One thing to watch out for when you pick your shock and set them up, is that the shock hits the bump stop before your ball joints bind up. Because you're using longer travel shocks with stock a-arms, you might run into problems. If your ball joints bind before the shock bottoms out you can have a mess on your hands if you ever bottom out hard on a jump, because it could easily break a ball joint or pull it apart, sending you over the handlebars with a cartwheeling quad in close pursuit.
I wouldn't put one of these kits on anything I own, I just don't think they're safe for aggressive riding, but if you're careful you shouldn't have any trouble. I'd just be cautious about pushing the limits with jumping it.