I have Dragon Quest IX on my DS. If you're not familiar with the series, they're epic Japanese RPGs with their own style. Dragon Quest VIII on the PS2 had an incredible amount of gameplay – I put 80 hours into playing it. From everything I've seen in DQ IX, and everything I hear, this tiny cartridge is packed with as much content as the PS2 disc.
For people not familiar with gaming, handhelds like the DS may not seem to be the place for epic games that last 40, 50, or more hours. It's too easy to assume portable gaming is casual gaming.
Of course this isn't true. Handheld gaming gave us Pokemon, games people could put hundreds of hours into playing. There are epic RPGs for various handhelds, from Golden Sun to Shin Megami Tensi: Strange Journey. Hand-held gaming has had epic for quite some time.
However, as I've played Dragon Quest IX, which proves to be more addicting than its' predecessor, I've started to speculate that epics are not only well-suited to handhelds, they may be an ideal place for them in the future.