There really aren't too many changes to the V-Rod since its introduction:
- Last months of '02 - Factory alarm now standard
- '03 Models - moved intake air temp. sensor to airbox
- '04 Models - 150 MPH speedometer, 28T sprocket now standard
Other than that, most of the changes are cosmetic. '03 Models all had the anniversary logo molded into the crankcase (to prevent fakes).
Just my $0.02 worth - but the original VRSCA in anodized silver is still by far the best looking V-Rod out there. Almost guaranteed to become a classic, especially if Harley does not resurrect this color scheme. The anodized silver is "unofficially" still the favorite among Harley's design staff.
As far as reliability is concerned, I'd say you have far less to worry about than on most other bikes. I've heard from very well-informed Harley sources that they have test bikes with well over 200,000 miles on the original engines - and no work needed other than oil changes and valve adjustments.
I've got close to 10,000 miles on my V-Rod, and I haven't had a single problem that wasn't at least partially my own fault (and these were pretty minor). It did "weep" a tiny drop of oil or two near the valve covers, but this seems to have stopped in recent months. I change the oil (Syn3) every 2000 miles religiously.
Make sure any bike you buy has a good service record. The seller's dealership will print up a service history if you are concerned about any problems. If he does his own oil changes, then he should keep copies of the receipts for his oil and filter purchases, along with the mileage.