(CNN) -- If you want to buy a consumer-friendly tablet computer today and you don't want to purchase Apple's iPad, you're pretty much out of luck.
The iPad currently has no real competitors, and the touch-screen computer is so far ahead of the market that it has some gadget makers running back to the drawing boards, according to technology industry analysts.
"In essence, what Apple has done is created a wake-up call to the rest of the industry -- that they need to look at what they're offering," said David Daoud, research director for the firm IDC. "They raised the bar significantly."
Tech analysts still expect as many as two dozen different tablet computers to go on sale before the end of the year. But they say it's questionable whether any of the devices will be able to replicate the iPad experience, which includes not only hardware but also a phone-like operating system, a touch-screen interface and a robust app store.
Meanwhile, it appears that some of the most-talked-about iPad competitors may be getting retooled to better compete with Apple's high-profile gadget.
The HP Slate and the Microsoft Courier -- two prototypes of iPad-like devices -- were both expected to go on sale later this year. Microsoft has scrapped the Courier, according to the tech blog Gizmodo; and HP is reworking the officially unnamed "Slate" after its acquisition of the phone-maker Palm, according to the blog TechCrunch. Neither of those reports was confirmed by CNN.
Apple's success is "causing a lot of tablet entrants to rethink what they're bringing to market and how it's being used by consumers," said Van Baker, an analyst at Gartner Inc.
Baker's company predicted that, of the 10.5 million tablet computers he expects to be sold this year, the majority will be from Apple. On Monday, Apple announced it had sold 1 million iPads in the 28 days since the gadget went on sale.
Other tablet makers will have to get in the game soon to have any chance of competing with the Cupertino, California, company, which also makes the popular iPhone and iPod, said Ashok Kumar, senior technology analyst at the investment group Rodman & Renshaw.
"You need to have a product on the shelf by fall to make the holiday deadline," he said. "If you miss that window of opportunity, you essentially give Apple an insurmountable lead."
Leslie Fiering, a researcher at Gartner, said as many as two dozen consumer-friendly tablet computers -- also sometimes called slate computers -- will debut by the end of the year. It's unclear who the main competitors will be, she said, but it may take more than a year for other companies to create a product "ecosystem" that is as useful as Apple's.
"Don't be dazzled by what it looks like," she said of iPad rivals. "You've got to be looking at overall usability and make sure that the apps are there and that the device really does what you're buying it to do. It's not a simple thing."
Daoud, from IDC, said he doesn't expect any iPad alternatives this year, in part because the iPad has been so successful.
He expects Apple to come out with a new version of the iPad before another tech company takes its first swipe at the idea.
Despite the positive reaction from analysts, there have been complaints about the iPad.
Some tech writers have bemoaned the fact that the device doesn't support Flash-formatted video and animation. Others hate that it's not easy to print from the iPad, and that it doesn't have a standard USB port for connecting other gadgets. The iPad also doesn't have a camera, which some said would be useful for video conferencing. Its touch-screen keyboard is tricky.
Some owners of Wi-Fi-only models of iPads, which went on sale April 3, also have reported difficulties getting or maintaining Wi-Fi connections on the devices.
But, as Fiering emphasized, Apple does have a robust app store and tablet ecosystem, which means there are interesting things to do with the iPad, like play games, rent movies and download e-books.
That may not be the case for its upcoming competitors, she said.
Kumar said tablets that run Google's Android operating system, which is already used on smartphones like the Droid and Nexus One, will have the greatest chance of success.
"You need a credible competitor, but so far there's not one," he said. "If there's one that emerges it likely will be in the Android camp."
A number of companies, from cell phone makers like Samsung and Nokia to computer manufacturers like Dell and even search giant Google, are working on Android-based tablet computers, according to unconfirmed reports.
HP's Slate was said to run Microsoft's Windows 7, the operating system that's common for PCs, but, according to analysts, may not work well on tablets.
HP recently bought Palm, a cell phone maker, and could use Palm's quicker webOS platform for its upcoming tablet.
Phone operating systems work better on tablets than standard computer operating systems because people control tablets by touching them, not by clicking icons with a hardware mouse, said Baker, the Gartner analyst.
Windows also boots more slowly than a phone operating system like Apple's or like Google's Android. Think about how much longer it takes to start up a desktop computer than a phone.
That's a turn-off for modern tablet users who've seen the iPad, Baker said.
"These devices are sort of impulse devices. You pick it up, you do something with it. You open a book. You want to look up something on a map," he said.
"And if it takes longer for the system to boot up than it does to do the task you want to do, then it's kind of counterproductive and people are unlikely to use them."
It's unclear exactly what the leading rivals to the iPad will look like, and who will make them, the analysts said.
But one thing is clear: They will have some catching up to do.