I've had my lifetime shed for 5 or 6 years.  Never had a problem with it until there was a hail storm that passed through recently with tennis ball size hail.  It took out the sky light that is at the peak of the roof leaving large holes in it.   But because I've never had a problem with it,  he said they would ship out a new sky light for free. He was very helpful and literally made my day.  
I highly recommend Lifetime sheds to anyone in the market for one.  They are great and customer service is pretty awesome too.