Not all that much, it turns out.

When is the last time you heard about a product introduction where initial sales were off by 90% barely three months after coming on the market?

If you’re thinking the Blackberry 10 … you’re wrong.

It’s the Apple Watch. Its introduction in April was made with a big amount of fanfare, promoted before and after the launch by PR, TV and online advertising, and even outdoor billboards.

But the hard truth is that aside from the tech community, few people are buying the Apple Watch.

According to Slide Intelligence, weekly Apple Watch sales have plummeted from around 200,000 per day at launch to fewer than 20,000 per day now. Moreover, most sales have been of the least expensive Sport model ($349).

Even worse, of those who have purchased an Apple Watch, fewer than four in ten would recommend the device to others.

You know there’s a problem when a new product engenders ridicule such as this brief, highly dismissive video review.

It may be too soon to write off the Apple Watch introduction as an abject failure. But I know one thing: The market’s (lack of) receptivity so far can’t be what Apple execs were hoping for.

It must be quite a comedown for a company that experienced the dizzying popularity of the iPod, iPhone and iPad right out of the box — and where those product sales continued to climb at an increasing rate for months or years after their debut.

Some people are comparing the Apple Watch introduction to what happened to Google Glass – likewise the victim of tepid sales to the point where Google quietly removed the product from the market after making a go of it for about two years.

Actually, I’m not quite sure the comparison is completely apt.

For starters, Google Glass didn’t come on the market backed by a ginormous PR and advertising campaign. In fact, it wasn’t really presented as a full-blown product – but more like a project with a beta test component.

Also, it was never made available in wide release; some people I know who wanted to “kick the tires” with Google Glass had difficulty finding out how they could do so.

But besides the very different rollout strategies, another factor might explain a more fundamental difference – and which has hugely negative potential impact on the Apple Watch.

Whereas Google Glass offered its wearers some truly new functionality, what does the Apple Watch deliver besides being merely a miniature version of an iPhone?

When something is less user-friendly (too miniature for many) … doesn’t offer any new functionality over alternative products … and is pretty expensive to boot, is it any wonder that the Apple Watch’s debut has had all the pizzazz of a cold mashed potato sandwich?

Speaking personally, I don’t consider a multipurpose device about an inch square in size as a “must-have” gadget, and I’m pretty sure others would agree with me.

Technology writer and CRM specialist Gene Marks cautions that the Apple Watch’s future isn’t likely to be much brighter than its less-than-impressive performance to date because of this fundamental liability: “The Apple Watch is not making people or companies quicker, better or wiser,” he contends.

In the world of technology and gadgets, that’s not recipe for success. Just ask Blackberry.

Now … let’s hear from Apple Watch users.  What’s your take?