Intel Core i5 4670 is worth the extra money... It has high better single/multi threaded performance then 4430 and has better memory performance too.. thus its price is high... If you plan overclocking then get i5 4670k....
What is your main purpose of buying this product? If you are gaming then blindly get i5 4670... If you plan overclocking and gaming then opt for Intel Core i5 4670k....