Worth is something only YOU can determine.
The GTX660ti FTW signature ($290 after rebate) is very good.
If budget is the issue, look for a non FTW or superclocked version.
You will get fair value for your money at every price point
Or... look at the GTX660 superclocked for $220 http://www.newegg.com/Product/Product.aspx?Item=N82E16814130826