I put some time into this over the weekend and it really is addictive - hours just flew by. For some reason, having it on a portable makes it that much easier to waste the hours away. It seems to go by a lot more quickly than previous Dragon Quests, and it definitely seems a bit easier in the beginning. Probably helped by the fact that you can choose to avoid a lot of the enemy encounters now (though it makes holy waters a bit pointless).
As much as I love it being on a portable, though, I have to say the DS's technical limits (or rather Level-5 pushing the DS's limits) are a bit distracting - the 2d sprites vs. 3d characters, framerate drops, etc. I've never considered myself a graphics or tech. whore, but this is one area where technical limitations actually seem to interfere with enjoying the game. I actually kept my party at three characters (which has been fine) to avoid taxing the system. Hopefully DQX on Wii won't be quite so bad (and maybe they'll return to portables with 3DS, where there'll be both portability and decent power).
I'm also not 100% wild about the translation, mainly the attempts at heavy regional accents. I appreciate that it's a lot more effort and character than goes into most translations, but it can be a bit distracting with the phonetic spellings of Scottish, Irish accents, etc. (I'm also playing through DQIV at the moment, where the accents are even stronger and borderline offensive - e.g. stereotyped Russian and Indian English - is there an equivalent in the Japanese text?) I can't imagine what a pain it'd be to parse the meaning of some dialogue if English were not my first language. Maybe it wasn't as noticeable in DQVIII because the voice acting meant you didn't have to read through a bunch of "guv'na"s and "blimey"s.
Those complaints aside, though, still a great game. Playing it at the same time as DQIV really highlights the differences / improvements from previous games that make it a bit more accessible, while still maintaining the DQ basics.