Very new, pretty, and good!
But SO confusing!
I've been to Lotte about 3 times, and each time I had to meet friends there were misunderstandings about where to meet.
The problem is that there is an older mall, the Lotte World amusement park (also the ice skating park nearby) and then the department store, and another part whose name I forgot.
In any case, make sure that you decide a specific point to meet up!