I've got them, but if you're just starting out, I wouldn't recommend them.
They do make things easier for transfering to kegs, and for harvesting yeast, but for improving the quality of beer, they really don't make that much of a difference
There are a lot of other investments that can be made that will improve beer far more than a conical. Full boil, temp control, all grain equip (lets you make more styles)...especially when you figure in the cost.
I built a single tier rig for not much more than what I now have invested in conicals.