The numbers are in, and from a sales perspective at least, Amazon.com Inc.’s Prime Day appears to have delivered on Amazon’s prediction that it would be a bigger than Black Friday, the day after Thanksgiving when holiday sales typically soar.

Amazon, No. 1 in the Internet Retailer 2015 Top 500 Guide, says it sales were 18% higher Wednesday than on Black Friday 2014. They were also up 266% compared to the same day last year, which was a typical July Tuesday with no big sales. “Going into this, we weren’t sure whether Prime Day would be a one-time thing or if it would become an annual event,” said Greg Greeley, vice president of Amazon Prime. “After yesterday’s results, we’ll definitely be doing this again.”

Merchants that sell on Amazon also sold a lot, although perhaps not as much as they did on Black Friday.

ChannelAdvisor Corp. reports same-store sales for its U.S. clients that sell through on Amazon increased 93% on Prime Day from the same day last year, with its European clients experiencing a 53% spike. But ChannelAdvisor says its merchants sold 3% less on Prime Day than they did on Black Friday 2014 and 40% less than on Cyber Monday, the Monday after Thanksgiving.

“What this means is, effectively, Amazon delivered on the pitch and they came within 3% of delivering a holiday sale in July that was the size of Black Friday,” says ChannelAdvisor executive chairman Scot Wingo. “In the first time trying this event, Amazon has created a summer shopping holiday as big as Black Friday. Amazon has exceeded our expectations for Prime Day.”

Amazon says it sold more than 34 million items on Prime Day. Matt Nemer, an analyst with Wells Fargo, broke down sales by category, saying that by his calculations, “32% of the sale items were in men’s/women’s fashion, 18% were baby/kids products and 16% were in consumer electronic categories including cellphones & accessories, and computers.”

Not only were sales up dramatically, so too was traffic to its site. Data from web measurement firm Experian shows that Amazon got 83.3 million visits to its site on Prime Day on desktop and mobile combined, beating its Black Friday traffic numbers by 77.2%. 

At least as important for Amazon, the sale achieved its goal of generating sign-ups for its Amazon Prime loyalty program, which provides consumers with free two-day shipping and other perks for a year for a $99 fee. Wednesday’s sales were only available to Prime members, including shoppers who signed up on the spot, and the e-retailer says it signed up more Prime customers on Wednesday than on any other day in the program’s history. However, Amazon did not say how many new members signed up. Amazon does not disclose the number of consumers who belong to Prime. But Investment firm Macquarie estimates 40 million U.S. consumers belong to the loyalty program. They are very lucrative for Amazon, as Prime customers have a 74% conversion rate, according to traffic measurement firm Millward Brown,

There is evidence many consumers were signing up for Prime during the sale from website performance monitoring company Dynatrace, which said Wednesday that the Try Prime page was loading far more slowly than other pages on Amazon’s website.

“From a technical standpoint, I feel like they were ambitious and by being ambitious they got caught [in a slowdown] for a number of hours, fixed it, mitigated it and managed through it,” David Jones, director of sales engineering for Dynatrace, said Thursday

Amazon’s biggest technical win, Jones says, was having no major meltdowns despite a significant traffic spike Wednesday.

“There was no situation that I saw yesterday where we got one of those sitewide messages saying we’re experiencing technical difficulties, come back soon,” he says. “We didn’t see a sitewide crash, we saw slowdowns in certain services.”

Data from website monitoring firm Catchpoint Systems also indicates that Amazon performed well technically on Prime Day.

Catchpoint reports that Amazon’s site loaded on average in 3.18 seconds on a desktop on Prime Day, slightly faster than the 3.28 seconds it takes on a normal day. There also was a slight speed increase on mobile devices, with Amazon loading in 1.51 seconds on Prime Day versus 1.59 seconds on a typical day. Catchpoint attributed the faster load times to the fact that Amazon trimmed down the content on its home page, which would help it load more quickly.

So was Prime Day a win overall for Amazon? That depends. Nemer says the sales numbers speak for themselves, and the promotion gave Amazon a lot of additional exposure.

“We believe Amazon’s first-ever Prime Day was likely a success, based on the number of products that sold out throughout the day,” he writes. “Prime Day also allowed Amazon to showcase the breadth of its offerings—from coconut oil to engagement rings—for those who primarily stick to the more obvious categories like books and consumer electronics.”

But not everyone sees it that way, with some analysts taking note of the many negative comments on social networks about the disappointing quality of the goods put on sales, items quickly selling out or long load times.

“Overall for Amazon it was a mixed bag,” says Colin Sebastian, an investment analyst with Robert W. Baird and Co. “On one hand there appear to be some disappointed consumers.  On the other hand, it clearly was a success in terms of volume and order flow, and perhaps next year they will be able to set expectations better.”

Paula Rosenblum, managing partner at Retail Systems Research, stopped short of calling Prime Day a victory for Amazon. “I see it more as stooping to conquer,” she says. “Still, Amazon is claiming traffic was huge, so perhaps they feel it was good.”