There have been grumbles from UK-based tennis fans this week about the quality and ease of watching Amazon's groundbreaking coverage of the US Open.
As the final Grand Slam of the year approaches its climax next week there have been a plethora of complaints about the live action on Prime Video, covering everything from picture and sound quality, to camera angles, ease of navigation around the service, restricted match choice, and the short duration of highlights.
User feedback on Amazon's own website has been critical, giving its coverage from Flushing Meadows, New York, just one-and-a-half stars out of five.
Remarks such as "At the moment the move to Prime Video for tennis fans in the UK is a backward step and very disappointing to put it mildly" and "this is just terrible - tennis fans in the UK are in shock about this 'service'" give a flavour of the disgruntlement.
After spending a reported $40m (£31m) to secure the tournament rights, the US online retail giant will need to sell a lot of Prime subscriptions - which cost £79-a-time in the UK - to recoup its outlay.
Hence its pledge to tennis fans that it is "working with customers to address specific issues" and listening "to all customer feedback".
Despite those viewer criticisms, within the sports rights industry the coverage is seen as a landmark moment because it is the first time Amazon has shown live action from a major global sporting event.
In doing so, it is moving into territory that has been the preserve of traditional broadcasters such as the BBC and ITV, or cable firms such as Sky and BT.
The move sees tennis move away from traditional TV to an "over-the-top" (OTT) offering, selling directly to consumers via the internet - and bypassing traditional telecommunications, cable or broadcast television service providers.
Premier League football
Over the past few years online platforms have invested heavily in content as they battle with those more-established formats for supremacy and customer viewing. Amazon has been among the most aggressive as it seeks to grow its subscriber base but has until now mainly focused on comedy, drama and film.
The firm made its UK sporting debut this summer, when it provided live coverage of the pre-Wimbledon Queen's tennis tournament in London.
And its gatecrashing of the tennis world has seen it also go for year-round content, after it secured ATP men's global tour rights for four years at a reported cost of £50m.
It means Amazon Prime members in the UK and Republic of Ireland will have access to 37 ATP World Tour events.
But it has not stopped there. After months of speculation Amazon announced it would bid for top flight Premier League football rights in England. In June, a deal was announced that Amazon was to livestream exclusive coverage of 20 matches a season online.
The online giant will show 10 matches over one Bank Holiday and the same number during one midweek fixture programme, for three seasons from 2019.
It should be available to UK Prime Video members at no extra cost to their existing subscription.
Someone who has been taking a close look at what Amazon has been doing in both the worlds of tennis and football is Robin Jellis, editor of specialist broadcasting publication TV Sports Markets.
"People have been saying the US Open coverage has not been without its glitches," he says. "But generally, with any streaming service, it will have some problems at launch."
He says that Eleven Sports, a firm that streams matches from Italy's Serie A and Spain's La Liga in the UK, has also had problems setting up its coverage.
"Any over-the-top provider has teething problems when they launch, and I don't think everyone expects it to go totally smoothly," he says.
"I don't think Amazon went into this thinking everything would be 100% perfect. It is practically impossible to launch something like this and have everyone happy with it."
Amazon's coverage of the ATP men's tennis circuit begins in January next year and runs until the end of 2023.
"The US Open is almost a test event for them to see what they can and cannot do," says Mr Jellis.
"Maybe this came a bit too early for them, they will want to add new features down the line. By next January they will hope to have smoothed out any problems and have a better service for customers.
"And they will certainly want to have everything right by the time they start their Premier League coverage in the 2019-20 season."
Meanwhile, tennis fans will be hoping for a more smooth Amazon Prime viewing experience from the Big Apple this coming week as the Open heads towards its climax.