Mediocre game as of post. It has tremendous potential but is currently lacking quite a bit in season 1. In its current state, I confidently can say that I feel Blizzard was woefully unprepared for this title release. It feels like a beta test rather than a fleshed out exciting game.
My biggest complaint is that it doesn't have desirable replayability. Once you fully level a character and complete all the quests both main and side, it gets boring. The monotonous grind and eternal quest for awesome gear hits a giant wall and feels about as exciting as waking up for work on Monday.
For all their excitement about customization, their catalog is painfully bare. The forced online play experience causes lag and rubberbanding constantly making it difficult to enjoy the intended mechanics.
Overall, especially after all their hype leading up to launch this year, this game is currently underwhelming and has a LOT of growing to do if it wants to survive the long haul.