Overall, I really enjoyed Millennium - A New Hope. It's a solid RPG with a good blend of challenge, interesting characters, story, secrets, large dungeons and a bit of humor. If you hate RPG Maker games, you won't like it no matter what I write here, so keep that in mind. For the rest of you, I'd say there's a lot to like in Millennium.
The game itself is a 5 part series, so keep that in mind when buying it. If you're thinking about the Millennium series, you should start with this one (obviously). You're then allowed to export your characters (with their inventories) to the next game after beating it. There's at least 20 hours of gameplay here, I think I finished it in hard mode at about 25 hours. I normally never play games on hard mode, but I did with Millennium and I enjoyed the challenge and extra achievements. There are a number of interesting and challenging achievements for this game. There are 24 secret rooms scattered throughout the world, 40 quests (both main and sidequests), and a lot of hidden things.
Combat is fun and challenging. The boss fights are pretty epic and there are optional tough "animal kings" for you to fight as an extra challenge after beating the main boss. Level design is well executed. The secret rooms are challenging to find and some of the dungons are HUGE with lots to explore. Luckily, there is an option to have arrows occasionally point you in the right direction if you wish. Unlike some other Aldorlea RPGs, you get the option to have enemies visible on the map instead of random encounter pop-ups after so many steps. The plot is solid, if not ground breaking and keeps you on track. I would say the plot speeds up and becomes more complex in M2. The music was enjoyable as well.
I only have a few complaints that are pretty minor. Early in the game, gold is pretty rare! You'll need to be a bit careful with your purchases. The economy is tight so don't expect to buy 99 of every healing item, etc. My only other complaint is that there is an achievement for beating 30 quests with the last character you recruit for your party. In order to get this achievement, you need to actively avoid completing any quests for most of the game and then come back to them after beating the main boss. This is a bit anticlimactic. If you don't worry about this achievement, it's not a problem, however. Other than that, it's an excellent RPG that's well worth your time. If you're on the fence about this game, there's a free demo from Aldorlea's website that lets you play the full game for an hour to see if you like it.
I hope this review gets you excited to try the Millennium saga!