EEs are coming out more and more now.. they are becoming the "new thing to have". I have some lol.. I fell for their big fins too :P Planning on breeding them - or attempting as Elephant Eared (also known as dumbo) is very recessive..
Salamander (the one in the picture) seems to be the typical coloration for them, normally PKs.. only seen a handful that weren't salamander in color (saw a blue/while butterfly long finned HM EE boy once at Petco - kicking myself for not getting him). So the color, pretty as it is, isn't special as most pet store EEs are that color.
Care is the same as all other splendens..
As for aggression.. they are betta splendens.. they are aggressive with one another like all other bettas. Nothing special about them other than a large pectoral fin.