Working in the tire industry myself, I see a couple times a week the negatives with adding wheel spacers onto a vehicle. They completely change the geometry of the steering and suspension, a lot of times in a negative manner. Also, you absolutely have to make sure they are torqued to the hub properly and than the wheels are torqued to the spacer properly. If they are not, than you may have a wheel come loose while driving. I have seen this happen first hand. It's also important to make sure they are "hub centric" as putting non hubcentric hub spacers onto your vehicle puts the entire weight and road force on the lug studs. Lug studs are not designed for that force as they are just designed to hold the wheel to the vehicle. The hub lip actually holds the weight of the vehicle. Additionally, they add additional wear and tear to your hub/suspension components.
In a nut shell, I would suggest NOT getting them. If you do though, understand the risks involved with getting them. You would be better off and safer getting yourself a nice set of aftermarket wheels that are hubcentric if you want an offset look.