It is always suggested to only ever purchase extended warranties backed by the manufacturer themselves. They are more reliable and trustworthy than 3rd party solutions, and also accepted at any dealer. There may be some sort of deductible for each claim under the warranty, but you are getting the vehicle repaired at a facility that has access to the latest TSBs, diagnostic equipment, factory specific tools, and overall familiarity with the vehicle. The dealer has a direct line to the manufacturer's warranty department and can get approval quickly for repairs (and will have no issue getting paid for the work.) In a majority of cases, it is a no hassle experience and works just like the original factory warranty.
When you get in to 3rd party extended warranties, you are at the mercy of an "insurance company" who will approve or deny claims on the basis of a diagnosis from a potentially inexperienced independent technician. Payment for repair can be delayed if the 3rd party is slow to release payment. The warranty contract itself is also at risk if the company were to go under. It can also be difficult to contact representatives from the 3rd party companies or have constructive discussions with them about claims. The 3rd party warranty may cost less at the beginning, but you definitely get what you pay for with 3rd party warranties.
Also remember that the price of the manufacturer-backed extended warranties is definitely negotiable. There is profit built in to them for dealers to make money on them. If the dealer you buy your car from will not budge on the price, you can always find another dealer willing to sell the Nissan extended warranty at a discount. There are several dealers online that will gladly sell the warranty to anyone that calls at a substantial discount from the "list price".
