The Radar function is fine, I guess? It's useful when 100%-ing the level with the Box Tally Mode enabled, since there are several monitors in places that are outside of the box. However, my personal problem is that it somewhat kills the feel of exploration and search for boxes completely blind, like it was in the PS1 Trilogy. Without the Radar, you are encouraged to go and explore stages, while with the Radar, you really just follow directions and don't do anything else.
It IS something that I can nitpick on when talking about the Emblem Radar in the Vanilla SRB2 for the same reason.
I know that it's a toggle-able function, but even then, it's really just a weird feature to me personally.