A few UI bugs and inconsistent descriptions that I've encountered so far:

• Drop down menus(like choosing difficulty of Tarot) are bugged and don't properly open.
• Precognition psychic ability. Skill description says that it gives you 100% damage reduction, with each hit you take reducing duration by 5 seconds. Actual buff in game says that you get 100% damage reduction, with each hit reducing damage reduction by 5%.
• Personal Void Shields. Skill description tells you that the shield can take 4000 damage. Actual item gives you only 2000 shield in game. 
• Masteries don't always update the stats in the description. For example, extra duration mastery will rarely update the duration in the description of the skill.