Though it is still early in the migration process, Apple's iPad and other tablets appear to be a very good thing for the publishing industry, allowing publishers to monetize their content while avoiding the printing and distribution costs associated with traditional print vehicles. And they've proved to be very good for consumers, offering improved convenience and portability, not to mention the ability to read in the dark.

The best app editions provide expanded service to their readers, making it easy to share articles through email or social media, find or buy products that are featured or advertised, and compensate for disabilities with larger font sizes and audio.

But there is a large problem that threatens to limit publishers' opportunity. Of the 5,000 magazine and newspaper iPad apps we've evaluated for McPheters & Co.'s iMonitor service since April 2010, far too many simply do not work well.

In the summer of 2010, about 45% of the apps we evaluated revealed significant malfunctions. That proportion is falling, but not quickly enough: Our analysis shows that about a third of all apps we have evaluated still have at least one serious shortcoming.

The biggest issue revolves around authenticating print subscribers. Authentication errors, in which the app fails to recognize existing subscribers, are reported for almost half of the publications that offer digital versions free to print subscribers.

But there are a host of other issues. Pages, video and audio can fail to load. Links may be broken. Audio sometimes won't turn off, leaving users the choice of closing the app or continuing to listen against their will. Spontaneous crashes are common. Downloads continue to be a problem with many apps, particularly when consumers want to download issues over a 3G network or without high-speed connections.

According to Mike Haney, chief product officer for Mag+, the responsibility for malfunctions can reside with the publisher, the development platform, or even the device if memory is constrained by too many apps running simultaneously. In the case of authentication issues, publishers' subscription fulfillment houses can also be to blame.

Wherever the problems lie, more aggressive testing is the best way to head them off in the first place. "Publishers can avoid many of these pitfalls by becoming better informed, following guidelines and testing applications thoroughly," Colin Fleming, digital publishing evangelist at Adobe, told me. "Bad links and display issues should be uncovered in testing, much like proofreading content before it's published."

It's also important to provide in-application customer service, with links to a website or answers for frequently asked questions, Mr. Fleming said.

Improved quality control and performance is essential if publishers want to ensure repeat purchases and maximized revenue. It's also important if publications are to compete effectively against other types of apps. News apps that don't come from magazine or newspaper brands malfunction with markedly lower frequency, according to our analysis at iMonitor.

Mobile platforms are rapidly transforming the media industry, and McPheters & Co. estimates that by the end of 2015, half of all magazine and newspaper circulation will be via digital delivery. Publishers have been successful in getting many consumers to realize that content is something of value for which they must pay. Now they must take pains to ensure that the quality of their products justifies the expenditure.