Ten years into the personal-computer age, the promise of massmarket electronic selling has remained just that -- a promise. Electronic shopping services, once heralded as the ultimate direct-selling tool of the future, receive mixed reviews from participating companies.

Some, such as MISCO Inc., a Holmdel, N.J., direct marketer of computer supplies, claim that they have done well by the new technology. MISCO is 1 of 49 advertisers that pitch their products to 185,000 subscribers of The Electronic Mall, a joint venture of Compuserve, the Columbus, Ohio-based information services company, and L.M. Berry & Co., a Dayton Yellow Pages publisher.About 20% of the database users place orders, says MISCO marketing manager Kay Braun, as compared with the standard 2% to 3% return generated by the company's printed catalog.

While businesses that sell computer-related products claim the best results, the potential for success is not limited to any one industry. Max Ule, another Mall merchant and a discount stockbroker in Manhattan, has signed on more than 300 customers in such faraway places as Alaska, Japan, and Puerto Rico by selling to them electronically.

Record World Inc., a $30-million, 60-store record and video chain with stores throughout the Northeast, has high hopes for future sales now that compact-disk recordings are part of its database of 5,000 record titles. "The type of people who buy and use home computers are the first ones to buy compact disks. It is a natural market," says Thomas Pettit, Record World's merchandising director.

Other Mall merchants are less enchanted with the service, however. Some say that price changes and merchandise additions aren't made quickly enough. And many warn that you must be prepared to devote your own or an employee's time to setting up and servicing the Mall. "As far as I'm concerned, it's been one big bust," says George Cowen, president of Big T Parts Co., a Detroit direct marketer of auto parts for classic cars and auto-repair manuals. "We sold exactly $1,198.08 worth of merchandise in nine months and [spent] $10,000 in time and entergy. . . . Until there are 15 million computer shoppers, not 150,000, I don't think it holds much appeal."