You should quote the context and article, it reads very differently then.
Your quote about them being unhappy with them is actually unhappy with a failure:
The plane may remain grounded for at least another four days while Boeing sends spares and a recovery team.
“These problems are unacceptable because this aircraft has been flying for the last 14 months,” Al Baker said, referring to the Dreamliner, which entered commercial service late last year. He added that Doha-based Qatar Air will ask Boeing to cover its losses. “Definitely we will demand compensation. We are not buying airplanes from them to put in a museum.
Aka, he's just playing hard ball for compensation for the incident. This could be because the contract specifically rules it out for commercial losses being an early purchase.
Lower down you will see his view on the aircraft itself:
Still, the performance of 787s delivered has been “quite adequate,” Al Baker said, and Qatar Air has seen no evidence of a separate fuel-leak problem that led the FAA a week ago to order inspections and repairs.
“Boeing makes fine airplanes,” he said. “We hope we will always work with them as long as they satisfy our requirements.”
That reads very differently from the assertion above taken out of context.
Article:
Qatar Dreamliner Grounded on Fault Echoing United Jet