With respect given to everyone's opinion, I do not believe that any of the modern exotics--except for a very select few Hypercars (e.g., Bugatti Veyron) or one-off creations--will hold their values for any significant length of time.
The unfortunate fact is that with the modern exotics, even the supercars, desirability is fleeting. Take, for instance, the Enzo. Initially, it was the very definition of performance and avant-garde style. But today? It seems positively dated. And it is. The entry-level Ferrari Italia performs virtually as well as an Enzo, is light-years ahead of an Enzo from a technology perspective and consequently far easier to drive well, is arguably more sexy and desirable from a styling perspective, and sells for "only" a fraction of what an Enzo costs. That spells real T-R-O-U-B-L-E for Enzo prices over the short to medium term. And they have been dropping lower for some time now.
Eventually, of course, due to its rarity and relative historical importance, Enzo prices may stabilize and perhaps even appreciate. But we're talking about a bonafide, extremely low-production supercar with some historical importance attached to it. Consider, in contrast, what is going to happen to prices of the non-supercar exotics, like the F430s? They are doomed. The only thing that has is holding 430 prices relatively stable (at the moment) is the fact that the Italias are in such short supply. But, eventually, supply will catch up with demand and enough Italias will be available to satisfy the limited number of buyers. Then we will see 430 prices depreciate a la the 360s.
Conversely, TRUE collectible exotics, especially the Enzo Ferrari-era vehicles, for instance, have been appreciating extremely well.
This dichotomy between the "old" and "new" Ferraris is a very interesting subject that author and noted Ferrari market expert Michael Sheehan writes about extensively for FORZA magazine and other publications.