I purchased both DQ Heroes 1 and 2 at the same time on a sale. I'm in the middle of Heroes 2 right now and finished the main story of 1. I consider DQ Heroes 1 more of an action game (with some RPG elements) than an RPG and Heroes 2 seems like more of an action RPG (more freedom of movement).
I never played Dynasty Warriors which is what this game is often compared to. DQ Heroes 1 is a mission based game which reminds me a little of Mass Effect's HQ and transport mixed with a DQ atmosphere. Your HQ has the normal DQ shops (except orbs replace armor), Priestess, Mini Medal, alchemy pot (not nearly as good as DQ8), Monster Suppressor (new), Patty's Place (choosing party), mail, and the most important - quest counter. The quest counter is where you get your side missions. Those range from the very easy to the very difficult.
I finished the story missions in Heroes 1 and am stuck at one pre-postgame (still active) quest which I'll go back to after finishing Heroes 2.
Graphics - B+ - It's similar to the DQ8 an DQ11 style of graphics.
Story and Atmosphere - A - This is where Heroes shines. If you played the DQ series from 4-8, you'll recognize the cameos of the characters. In Heroes 1, you have Yangus, Jessica, Terry, Alena, Kiryl/Christo, and Maya/Mara. One other playable character as well I won't spoil as he's also an optional boss. I think Healix is almost like Healie as well. That's not including the original characters from this game. The monsters are also the real stars of these games as well as any DQ game. The game has story missions, side quest missions, challenges, boss refights for treasure, and areas for grinding to get items/goals for sidequests or just leveling up.
Length - B - Solid length. The main game isn't that long, but the quests and missions bring new challenges. Money can be a bit of a challenge as well if you don't sell a lot of equipment. There are a lot of characters and it is expensive to buy for all of them.
Difficulty B-. The main story is too easy. I'm a former weekend warrior at best on action games and I normally have to get in gear before breezing through the bad guys. That aside, some of those optional mission quests are no joke and difficult requiring more than basic tactics (ie - kill everyone and put up good monster medals like golems and killing machines by the barrier to assist). Usually missions are one of two types. A. Kill the enemies B. Also protect the person/barrier. Luckily this isn't as bad outside of one case as those annoying Grand Theft Auto/Scarface The World is Yours escort missions where the idiot that needs to be protected goes out and runs into the path of silver batboons (or whatever they are called now).
Combat and Play Control (PC) - B - Mostly straightforward. AI isn't terrible for allies, but could be better. It's not that hard to switch control of characters.
Beginnings and Endings - B - Normal DQ style.
Bugs - B - No crashes. Sometimes my controller froze however which required me to take out and insert the controller again to get it going. That's a nightmare in the wrong spot.
Price - B - I paid $50 for both DQ1 and 2 on expanded editions.
Overall - B - It's a good spinoff. I hesitate to compare it to the main series as it's not the same type of game. If you liked DQ4-8 characters, it is worth a look.