Depends if your a collector, or just want something to wear out that looks half-decent, a lot of people here saying your a pykey for buying a fake, likewise your also a bit of a tool for paying some overinflated price for some mass produced watch that only has one function.
I have a replica Tag Heuer - Formula 1, I have compared it to a genuine model, and there is no way you can tell the difference, same size, same weight, same feel, same material ..... Considering the cost difference, my Tag cost a total of £40 including delivery, in the shop they are £720 (I do believe), so even if the watch broke once every 6 months, I could go for years and years and still make a saving. p.s. been wearing it everyday for 4~ months so far and no problems.
In the old days perhaps the designer watches where hand crafted, but today a Omega/Tag is as mass produced as the replica versions knocking around.
My advice is, unless your a collector or you want to start collecting them, save yourself a lot of cash and go for a replica, in todays age its basicaly the same thing, sometimes the inner works are different, but to be honest ... who cares?, as long as it looks genuine and tells the time, nobody will know.