Free trials can be... stressful. We recently even had a piece about trying to make the most of the limited time in them, if the point must be stressed. That's no doubt the reason why several companies have begun moving away from unlimited access for a brief time, and started to spread their trials out for as long as the player wishes. Warhammer Online, Champions Online, Free Realms, and Alganon all allow players a chance to try a limited portion of the game for as long as they want. And for someone without a lot of time, it's a perfect way to expand your window of playtime.
Of course, if you've got plenty of time to devote to the trial, it's a bit obnoxious to hit a hard limit before having really gotten to explore the meat of the game at all. For some players, the fact that they're giving away the starting area or first few levels tends to imply they're not good enough to pay for in the first place. Do you find unlimited free trials more tempting or less than the traditional model? Or do you see it as a sign that the game is in trouble or otherwise undesirable?