Not in the sense that I didn't enjoy it, and not in the sense that it is totally horrible, but in the sense that it doesn't do a number of key things that the Genre should do:
In my opnion, ARPG's and for the love of god, Diablo, should focus more than anything on Replayability. Diablo 3 has very minimal replayability. I'm not talkking about grinding. Grinding for items is the "ultimate" goal in these gmaes. I'm talking about the need, desire and FUN of clicking "Create" and starting a brand spanking new character.
It should feel like a fresh new challenge and be somthing that you think of like this "I can't wait to start a new Templar - I wan't to try out "X" build and "X" skill sets.
Path of Exile, in my expirience in beta, has this in spades. In the beta thus far, I have made at least 10 characters and leveled them to 30+, each time was a new route on the tree and a different focus on skills.
In Diablo 3, after 1000+ hours and 8 months of release, I have 4 characters. I never even felt the need (or desire) to make the final class as all the items in D3 work for every class the same (for the most part).
2: Amazing Itemization
Diablo 3's items are HORRIBLE. They are somewhat addictive to hunt for (need that perfect roll!), but there is no thought behind your gear choices. You want Crit, Crit Damage, IAS and your primary stat. Throw in some stam and resistance if you can. Thats it for EVERY class. This genre should have that feeling of "Ohhh snap, that item I just picked up would be AMAZING for "X" class or "X" build.
Diablo 3 Fails at that big time. Path of Exile on the other hand. Oh boy! Again in spades! For example - I had been thinking about building a Templar that would Focus on Lighting Strike and and use as many Auras as I could get mana for reserve. So, I wanted to use Eldritch Battery (A passive that takes your Energy Shield and converts it to mana) for a big mana pool. Well.. i happened upon a simingly "bad" pair of Unique boots that SCREAMED to me "WoW! These would be PERFECT for that build. It has 100% increased Energy Shield - of course not end game, but for a start to making a HIGH mana pool-Eldritch Battery build it would be awesome!
This is just the tip of the ice when it comes to the amazing items in PoE - you have to "think" when you look at them. You have to have them in mind when chosing passives. You have to have items in mind when chosing your skills. In short, the itemization is spot, on, perfect!
3: Skill system that makes you want to make new characters
This goes back a bit to replayability, but Diablo 3 has, what I thought to be, a GREAT concept for skills. 5 ways to use every skill! Sounds awesome right!? Well it is, except that you can use them all at any time.. so.. there ends up being no real thought process behind the system at all. In fact, the interface for chosing skills is so straightforward, it needs to be exlpained BECAUSE of how easy it is: "So, where are my skills points spent?" Answer: "You don't spend skill points, you just choise your skill" - Uhh.. ok?
Path of Exile uses what SHOULD have been the great concept in D3 and does it right. D3 originaly had Skill Gems - the thought of finding skills in the world was AWESOME! I remeber being VERY sad when the scratched the idea. They said "it was to hard to implement" or in other words "They didn't trust their players to be smart enough to be able to handle the inventory".
Enter PoE. Skills gems working beautifully and I love it! The room for expasnion to the system is endless. It truly is a thing of beauty!
Look, Diablo 2 (two!) did it wrong. Players had to make their own currency (Jordans) - Diablo 3 tried to make it so easy to trade your items that you barely have to think. The result - actual item hunting is nearly pointless. You instead are grinding gold / items you dont want but can sell / so that you cna make that next purchase.
PoE, once again, hits the nail right in the face. The economy seems SO great from my expirience in the beta.
I wanted a Tempest Shield Skill Gem recently. I could have replayed the first act and grabed one from a quest reward, but I had a Jewelers Orb and someone else with a Tempest Shield Gem was willign to trade. Was it fair? WHo knows really, but I was happy and he was.
Having an Auction House was such a bad idea in Diablo 3. It made items totally worthless - over time it has made only the absolute BEST rolled items worth anything at all.
You should have to do a little bit of work to trade your items in a game like this - why? Because some (most?) people won't bother. They will either save the item or discard it rather than search for a fair trade - that preserves the economy!!@!
5: End Game
This one is short: Diablo 3 had none at launch. Now it has a endless grind for a remakeable legendary ring. Soon, it will have craftable ilvl63 (endgame) 6 prefix gear to re reoll over and over and over. I'm sorry, but this doesn't cut it nowadays.
Path of Exile - Maps. Holy heck what an amazing idea (I know they didn't toally invent the idea) Having Maps be an itemzied system with rarities and properties is just awesome! So awesome! Your still doing the "grind" but in a fun way!
Lastly - I cant wait to devour this game (PoE) once the final reset happens tommorrow. I fully intend to play this game for a very very very long time. Everything I dislike about D3 is done right in this game - and I couldn't be more excited!