My experience is different from Ottergame's. Rifts is the epitome of the mish-mash setting. It mixes magic, technology, mecha, and supers into a setting. There are some great ideas in the game, but the system is horrible. Magic is extremely weak compared to technology. There is no sense of balance, and each subsequent sourcebook ramps up the power level. It's not all bad. Some of the books have some great ideas, like I said. I run a conversion of it using D20 Modern, and in a balanced system it's a lot of fun. You can have fun playing straight Rifts, but you need to have the right group of players and a GM that knows what exactly he'll allow and what he won't. If not, it'll turn into a free-for-all slaughter-fest with a wide disparity of characters. (One group I played with briefly had the following make-up: A core rules Cyber-Knight, an Atlantean Undead Slayer which was nearly unkillable, a Free Quebec Glitterboy capatain which was nearly as bad, a simple human vagabond, and a Jungle Elf Millenium Druid. Only the Atlantean and the Glitterboy survived the entire session, my cyber-knight lasted for about half the session, and the human and elf were dead in the first round of combat.)
I doubt that Rifts is targetted at a younger crowd, but that's the crowd that seems to play more than anyone. Palladium used to run ads for Rifts talking about it being an advanced system not suitable for RPG beginners. Doesn't sound like they were targetting the younger, and more likely "inexperienced" crowd there.
The reason you don't find any information about Rifts on the net is Palladium's OVERLY restrictive net policy. You can't post conversions to or from any Palladium system on the net. I don't think they like you to even post your own statted homebrew stuff.
Kane