First at all, I'll add images with examples of the issues I mention here when opportunities arises.
Second, in this topic I'll make the comparative between Legacy map and Frontline map where the former is better than the later, with the goal the GO and devs makes the proper corrrections over the beta version. Because of that, this topic will be heavily edited as I'll add the aforementioned images.
1. As you can see, I can outfocus the map in Legacy almost totally, that allows comfort to the user when he needs to manages troops in the extremes of the map. In Frontline, that's not longer possible and that comfort disappear (we need to zoom in to do the same management)
2. Do I need to move troops to a point outside of the screen? Legacy allows me to do that with no problem. Frontline, instead, not. For that, I need to select the troops and click on "move" option. Even then, the displacement isn't automatic as in Legacy, but I need to keep pressing the click to move the map for moving the troops outside the screen. In other ways, devs made complicated a simple feature.
3. This is, possibly, the greatest criticism many users has made about the new map when compared with the old one: in Legacy, you get a complete accountability of your army composition in a determinated place (infantry, cavalry, tanks, heavy tanks, artillery, armored cars, etc) without even select that army. Frontline, instead, just shows you the 3D unit who give the name to that army (that only suggest that army have, at least, one of those units. Still, I think that 3D unit is a good addition) and a shallow, even lazy, accountability of the army composition (while Legacy shows you have 28 infantries and 8 cavalries, Frontline just says you have 36 "human units"; while Legacy tell you have 5 artilleries, 5 light tanks, 2 heavy tanks and 8 armored cars, Frontline just tell you have 20 "mechanized units") that compelled the user to click on that army to receive a more detalled composition, that wasn't needed in Legacy.
4. The same images also shows another problem: the actual location of the armies in the map. Legacy is very clear signaling the army is IN the city; Frontline suggest you the army is OUT of the city. That's something totally and unneedly misleading for the user.
5. Continuing with the misleadings, in these images we can see Legacy shows us the exact location of the troops moving. Frontline, on the other side, want to indicate us the same things with white lines almost totally indistinguishable with some colors in the map (unlike Legacy, who give us that indication with well-defined black lines) and, as you can see with the arty, totally unneeded when that arty can be put on the road to show us its actual position. So, if you combine points 3, 4 and 5, the conclusion is that Frontline map gives the user unreliable information about the military situation.
6. There is also complains not only about the 3D units being gigantic when compared with the cities (in contrast with Legacy, where the size units are reasonable) but with the infantry being the most gigantic of all units (including cavalry or tanks). Of course, that disproportionated size takes realism away from the game.
I think Frontline, since the purely graphic design view, is, undoubtedly, a great improvement compared with Legacy (despite the fact the improves on graphics also means more lags in the game) and I congratulate the devs for that improvement. However, the critical issues related here (plus the excellent review made by Sandeep32) have the community concerned about the viability of the new map to attract new and old players. Fortunately, Frontline is still beta version, so the devs can takes notes about these issues and resolve the current problems that impairs Frontline to be the great map that it can come to be.