The Winter Wonderland NI festival near Bangor, Co Down, on Saturday featured a plastic ice rink with no ice, a disappointing Santa's grotto experience and queues of people complaining and demanding their money back, vendor Ben Harshaw said.
A series of negative comments were posted on Facebook, although parent Jennifer Neill said her child had a good time on the second day, Sunday.
Mr Harshaw was selling hand-made goods like stuffed animals on Saturday and did not bother going back for subsequent days.
He said: "There was just people complaining left, right and centre.
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"There were people who had booked specific times to see Santa and were left waiting, all that with three-year-olds and four-year-olds, kids crying, it was awful."
A series of unflattering photos and videos were posted online.
The organisers did not initially respond to requests for comment but posted their apologies and one Facebook user who co-ordinated feedback, Andrew Cowan, said he had received a refund.
A Facebook statement on behalf of the organisers said: "Winter NI would like to apologise for the Bangor Winter Wonderland event which has fallen way short of our expectations."
Mr Harshaw, from Lisburn in Co Down, runs NI:NY Creations and was booked to sell items made by his wife over four days at the pre-Christmas event.
"She spent a good month and a half, working until one in the morning making things and we had no opportunity to sell any of it."
He claimed they were in an easily overlooked room separate from the main thoroughfare.
"If you are getting the footfall of people and they don't like your stuff and don't want to buy it then that is fair enough, but because of where we were positioned it was impossible for us to even show our stuff."
His stall was in an art gallery at the Clandeboye Estate.
"All of the craftspeople with us, we had maybe 10 people in the room the entire day because of where we were put.
"Those people were p***ed off, they were not there to spend money."
He said he went to seek his money back (£20 a day) and there was a queue of parents waiting to complain.
Ms Neill took her two-year-old son on Sunday.
She posted on Facebook: "He loved the petting farm, the staff were great with him, he had a great time on the bouncy castle, Santa's grotto was nowhere near as bad as we had read online.
"He got a little box of books and a bag of coins.
"I don't know what it was like yesterday (Saturday) but we had a nice day and I'm glad we went."
The event was held at the Clandeboye Estate but was not organised or associated with the estate, which can be hired for events like weddings or functions.