This review seems to give a good overview as to what's what. Nice new graphics, old style gameplay and plot. Random encounters seem to be intact and at the same frequency as in the original game, i.e. quite high by modern standards, also comparatively difficult. There's a comments section linked at the bottom of the review so you can get quite a few other opinions.

I picked up a copy because it was so stupidly cheap (play.com, £17.99!) I thought it had to be a mistake and it would be back up to £24.99 very shortly, but I won't be playing it until I finish the GBA version of FFVI.

Actually, there's a possiblity for you. If you haven't already played FFVI get that instead. You can play GBA games on the DS.

Dragon Quest is on my wanted list too. The lack of an impending release doesn't worry me too much at present; I'm still playing through VIII.

Have you seen Magical Starsign? Another entry on my RPG to-play pile. It sounds like its fun to play, a bit different. Final Fantasy Chocobo Tales just came out too. Mini game filled card battling FF based weirdness. Opinion of it is generally favourable.