Yeah, I've got both. Dark Spire is old school wizardry. It is basically a sequel in all but name. It's hard, unforgiving, but a hell of a lot of fun - and you can either play with old school 8-bit music and visuals, or DS-quality art and music.
So basically a more hardcore version of Etrian Odessy. And better, IMO.
Deep Labyrinth is... not as good. I do like the game, but it's very simple, and if you're going in expecting a DS Oblivion you'll be disappointed.
What Deep Labyrinth does well though is tell a good story, despite telling it in tiny, tiny fragments.
Still, it's worth $10-$15.


Mickeymac is correct, EO is what you might call a watered-down version of DS and the Wizardry series, but it makes up for its less complex mechanics with a more accessible presentation.
Talking about a deep blow to the stomach, it hurt the whole time I watched the format bar fill. Bright side is Ive now changed classes from Royalty to Knight and the ability to push enemies right when they go to hit you and then instantly can counter the mess out of them is great. Also starting the game back up is much easier the second time. Now that my game collection has been drained way down I plan to spend a great deal of time with this one in my PS3.