Okay, it's great. Everybody says it's great. I get that.
Why is it great?
Does it cuddle after we make love?
Playing a game that requires a guide to play it properly doesn't sound too fun...
It's honestly more enjoyable to play it without one, learning from your mistakes.
As for what makes it great, aside from the fantastic plot and endearing characters, the system itself is ingenious, discouraging the brood and giving a real reason as to why they shouldn't be used and can't be controlled. Plus it's a jRPG that's actually difficult, and actively discourages mindless grinding (something even Nocturne is susceptible to, despite its brilliant fusion and battle systems).
Put another way, it's difficult due to its systems, not due to artifice, like Chrono Trigger is (excepting Spekkio and getting certain endings). A bit more specific - I can make any part of Chrono Trigger ridiculously easy by just spending more time at it. In other words, I can trivialize almost every encounter without a lot of actual thought. Dragon Quarter doesn't really provide answers that are always obvious, it requires a new and different manner of thinking about its systems at times to progress. Which is great, and it means that it's leveraging the systems in the game and fully extending and expanding them to create consistent interest.