The Last Remnant is the best 3D turn based RPG to hit the PC for ages. The union system allows you to control groups of characters by issuing a single command and while it might seem simplistic, the way you arrange your groups and what abilities you select for each character to use in combat makes it much more interesting, and the way your characters evolution isn't directly decided by the player, but rather managed by what you do makes it very immersive. As the player, you will need to pay attention to what a character's actions are in order for them to become stronger. Also the boss fights can resemble alot what an MMORPG boss fight is like, as you should assemble specific groups of characters, such as a group of healers and a tanking group, and getting the right characters to fill in these roles isn't as simple as to pick them up in a store, the player needs to develop the characters in a specific way if they are to become a specific member of the group, as you can't just put anyone doing anything.
The story is interesting enough to keep you going, having it's ups and downs, and the side quests are a nice break and chance to make your characters stronger.
The letdowns are how the item gathering system works, as it isn't always clear where you can get the items you need to craft or upgrade your characters, but a great wiki is present at http://lastremnant.wikia.com/wiki/The_Last_Remnant_Wiki_-_The_Last_Remnant_Guide
which has all the information you will need to help you with this. The main character is simple minded, childish and might not be your prefered one, but he's flexible enough to become strong in anything, so you'll find him useful.
This being said, the game is a great chance for people who have been wanting a deep and fun turn based RPG, specially on thethe PC who hasn't had anything like this in a long time.