AOL Time Warner's (NYSE: AOL) Internet service has always been a lightning rod for criticism. (Should we call it a criticism rod?) Citing higher prices and slower speeds, many predicted America Online's downfall at various points along the way. And yet, it kept raising prices, and new people kept signing up.

Until now, that is. The company reported a sequential decline in subscribers last week for the first time ever. Mind you, with over 35 million users, it's still far and away the world's No. 1 service. But many AOLers are waking up to the fact that $23.90 is a big chunk to pay for dialup every month, when reasonable alternatives are available for under $10.

United Online (Nasdaq: UNTD) , which operates the Juno and NetZero services, is a perfect example. Charging just $9.95 per month, United Online saw an 8% sequential increase in paying subscribers for its fiscal first quarter, and 48% year-over-year growth.

Throw in the fact that more and more people are moving to broadband, and you can see why AOL is getting hit coming and going.

But wait -- there's more. The number of Americans who surf the Web is no longer growing, one researcher told The Wall Street Journal. Jeff Cole of the UCLA Center for Communication Policy says about 71% of Americans used the Internet in 2002, the same as the year before.

So, AOL is losing subscribers to lower-priced services and to broadband, and there's not much growth on a macro basis. Its advertising revenue, buffeted from the industry meltdown by long-term contracts, is plummeting now that the contracts are coming due.

Not exactly a recipe for success, and a clear indicator of the challenges that lie ahead.