The Dragon Quest series is finally gaining popularity in Europe, but in its home country it's been a Final Fantasy beater all along, even in the NES days. As is popular on the DS, the older installments are being revamped to make up for the losses of European audiences in the past. I don't mind, as I've had little experience with the Dragon Quest series yet.
Compared to the Final Fantasy series, Dragon Quest installments never really reached the level of graphical and gameplay innovation. Probably the reason why they were kept from Europe altogether for such a long time. On the other hand, they provided more solid gameplay and stronger storylines. Keeping in mind that the original DQIV was developed for the NES, it's easy to understand why they are so popular.
DQIV brings a nice little twist to jrpg storylines. Rather than start off with the main hero, the first 15 or so hours are spent getting to know your supporting characters, when they start their separate adventures. When you finally reach the main hero's chapter, you can track them down one for one and start building your team. A very fun twist that has a pretty huge impact on the feel of the game.
Design-wise Dragon Quest has little on the Final Fantasy series. Original designs were made by Akira Toriyama (of Dragon Ball fame), who is no competition for Amano's designs. Still, the 3D look of the environment is pretty nice and dungeons look attractive enough. Character designs on the other hand are pretty limited, especially the enemies. In the though, that's just part of the Dragon Quest franchise.
The soundtrack is nothing special either. Typical jrpg music with little individuality. After a while I kept the music off (which is easier on the batteries too). While most musical scores on the DS aren't anything special, it would be nice to get some better music from time to time, especially on rpgs like this.
The game itself is pretty cheap when it comes to stat raising. It's not easy gaining levels and it's even harder to come by good money. When the best armor in the game costs about 35000 and you're only gaining 250 per battle, things can go a little slower than expected. Still, the game never becomes too difficult or impossible to beat and there's a healthy balance between leveling, equipment and challenge.
Exploring is pretty fun as there are many places to visit, there's even a difference between daytime and nighttime visits (which does become rather tiresome at the end of the game). This makes dungeons a little short from time to time, but keeps the interest going with many events going on and many places to visit. Side quests and secrets are a little scarce, but there's some town building to be done and some solid apres-game extras (new dungeon and even a new team character).
If you're looking for a solid jrpg on the DS, Dragon Quest IV is probably a very good bet. It took me about 50 hours to complete the whole package, there were plenty of things to do and many places to visit. The presentation is a little lacking from time to time, but it never hampers the fun. Add to that the interesting twist of the chapters and you have great handheld fun that will keep you occupied for quite a while.
If you're looking for more stimulation, try the Dragon Quest IV trailer.