Hooked Gamers has put together a preview of Titan Quest, based on what we know about Iron Lore's action RPG up to this point. Check it out:
Your hero will be able to specialize in any of over a hundred combat skills, including some pretty powerful magic. You start with just a basic avatar - male or female - and can then customize to your heart's content with over 20 character combinations, and over a hundred individual skills to choose from. Be a mighty warrior like Hercules, or a great spellcaster like Medea. The choice is yours. By eschewing the entire class-based system, you can expect to find a lot of variety in how players approach the challenges before them.