By the way, they have to adjust the amount of experience gained (or requirements per level). At the moment, it is definitely too much. When we finish act 1 (in full game), we will have about 6-7 lvl which is too high (there will be 3 acts in the game).
There's definitely enough XP to reach level 5 in the current version of act 1, but I don't think we'll be able to reach level 6 or 7.
Level 4 is 2700 XP
Level 5 is 6500 XP
Level 6 is 14000 XP