BUGS and bad support
From the nearly none existing costumer support (they them selves say they are severely understaffed), to the plenty full amount of bugs with events, recharging and new stuff they put into the game. When they added Dark abyss, normal abyss was bugged like hell for a week, you could win a perfect game and it would count it as every thing between a loss to a nearly perfect win, not the perfect win you got. At times when you try to recharge, it goes through on their 3rd party pay sites, but stops short of crediting your GTA account, it wont show up on the list of transaction on their homepage, but it will show up on you bank statement. Even if you take to the forums and to let em know about your problem(s), it can take weeks before someone from GTA acknowledges you, quite frankly astounding with all the money i believe they made over the past few months...