First of all I must say that this game is a pleaseant surprise, it is a really great experience!
So here we go:
>Energy System
It is a great idea I think. It's even better that you can buy it from players. But I Believe that elevators cost too much, it should be maybe 5 instead of 10, or have selected days, happy hours or something, where the energy cost of the elevators would be lower. I don't know how frequently players get Mist tanks, I got one after clearing the tutorial, but I believe that there should be random mist tank drops in the lower levels of the dungeons, or as a reward for the player who did the most damage, or maybe the ability to craft it (of course this would require a LOT of resources.)
>Healing
Now I know that there are healing pots that you get from time to time, but there should be a "weapon" that can heal others. I understand that if there would be healers that can heal constantly, the game would be a lot easier, but perhaps a bomb that can be used only once in a level? Same goes for buffs, I know that some armor give the wearar small damage bonus and things like that, but what if, you have an armor that buffs you, and you could make an aura, that buffs nearby players too.
>PvP, GvG
Now, I wasn't in the closed beta, but a friend of mine was, he told that there was pvp but it got took out, so that it could be worked on. I do hope it returns, PvP is one of the best things in MMOs! Also, I think that a GvG game should be added. There is another game that does this, but I won't name it because I'm pretty sure that it's against the rules, but if there would be a mode, where guilds compete to capture a point/castle/dungeon or steal flags or pots, it would be really neat, and I am sure pepole would like it, and it would be a big reason to join a guild.
>Votekick in party
Simple really, I know that party leaders can kick, but if the party leader is afk and you can't go on because of him, now that's just annoying.
So I guess these are my 2 (or rather 4) cents.
PS: I am from europe, and I'm not sure where the game server is located, I guess in America right? Well anyways, I had no porblems with lag that I noticed so far so great job guys! and khm, I know you just started but a Europe Server would be nice if you guys start earning big. (And you will, atleast I really hope so!)