I do not know how the map features worked as of yet but the ability to have maps that are animated was impressive. I could load a PDF of the character sheet and then define the form fields to be filled in. This was really cool to me as I loved it. The second one that I know of is Astral Table Top and though I am not as knowledgeable about it the thing that impressed me with it is that you can get a character sheet up with very little effort so long as you understand how to put form fields on a PDF background. Another plus on Roll20 is voice can be set up native though I don't know anyone that does that which also could be a con as it might not work well enough to use. Once you get into programming macros for dice rolls things start to get a bit more complicated but it doesn't change the system very much and I really don't like there sheet integrations. Learning curve is smaller for a GM to get up and running but it doesn't feel very flexible to me and a D&D game will feel like a Shadowrun game on the system which can be a plus or minus depending on what you like. It is a good program and can be used for free by players which is a plus and the subscription for GMs is not really that bad. The mapping is good for tactical combat but I am not a fan of the way they do things (their layering).
Though you will still need to possibly keep your character sheet off line or in PDF it does work well.
Many people use Roll20 and I have played 6th on it as well.