I've been playing JRPGs since the original Dragon Warrior and Final Fantasy on the NES, and felt I should weight in on this topic too since I did buy both games at release.
I am in the few minority that actually enjoyed Infinite Undiscovery. I beat it three times on the 360, got all 1000 Achievement points, and even
wrote a guide for the hardest difficulty on it. Infinite Undiscovery is a pretty standard JRPG for this generation, and hasn't done much evolving at all. It could have very well been a PS2 game - but to me the gameplay was still enjoyable.
I played about an hour or two into The Last Remnant after doing a full install on my 360 and I stopped playing it shortly after that. The questing, combat system, storyline, etc. just didn't work for me so I stopped it and got rid of it. In a way, I pick up JRPG games because I like the traditional elements that they possess - The Last Remnant was not what I would consider a traditional JRPG.
My argument for the two is that The Last Remnant tries a lot of "innovative" things, and if they work for you, you'll enjoy it more. But if you prefer a more traditional JRPG that actually plays more like an action-RPG, Infinite Undiscovery was good enough for me to play through three times. The characters and storyline were typical throwaway JRPG fare, but being able to jump and perform special attacks and seeing 9999 pop up on enemies was more gratifying that I expected.
Having said all that, none of these JRPG games compare to the SNES glory days though, but I guess we have to take what we can get in this day and age.