Rogues are great at what they do. Scout are equally as great at what they do. The difference, a Scout gray's the area between Ranger and Rogue just enough - ever wanted that somewhat in between class without multi classing - the Scout is dead on.
However speakinig of multiclassing, this is where the Scout really shines, add a few Scout levels to a Ranger or Fighter, or any Elf and the ranged combat leathality rises considerably. Add a few Scout levels to a Rogue and that first Flat-footed Sneak Attack made when the party wanders up on the unforseen monster; the Rogue can fade and still strike while limiting the amount of "in the way and in the line of fire" time to a minimum. A Scout and any offensive Spellcasting class makes a deadly combination, how about skirmish damage added to Ice Knife, very nasty indeed.
Rogues are by far my favorite class, I've played everything from the common criminal to a masterful diplomatic noble (and pretty much everything in between). When I play a rogue I am in my zone as far as Role-Playing so I will always be partial to that class, but I see the Scout as not a threat, but a long-missing member of the shadow alliance, along with Bards and Rangers, the Scout has finally filled the void in the base classes. I like them, and have seen them make quite a difference when played to the hilt.