Heroes of Newerth or Hon is an upcoming game much like DOTA, Its concept is almost the same.
You gain gold and experience by killing creeps or heroes.
The main difference is the graphics, HoN displays astounding graphics compared to DOTA.
I think people who used to play DOTA will have no problem adjusting to HoN but they will just have to study the items, recipes and skills.

Additional information:
Did you know that DOTA was heavily based on Aeon of Strife map from Starcraft and that icefrog isn't the one who created DOTA.
The orginal creator of DOTA was Euls then it was passed to Guinsoo and now the present Developer icefrog.

Below are screen shots of HoN taken from google:




Here is a video of HoN:


You can check Heroes of Newerth in their official website but it think it is still under construction
HoN