After you finish Diablo 3 on normal, you will start from the beginning of the game on “Nightmare” difficulty, you can still keep your gear and leveled character.
This is no news for the old school Diablo fans as the same concept was used for Diablo 2.
Why to play it further on “Nightmare” difficulty and even on “Inferno”?
You can finish Diablo 3 on normal mode by reaching level 28-33 if you didn’t grinded and restarted zones. For this reason, until you finish Diablo 3 on normal, you will have just around half of your class skills unlocked so you will miss some interesting combos.
Not to say that hardcore fans will want more. We can even sell items in auction house for real money but this feature is uncertain at this time, so far the auction house looks difficult to use.
The skill/runes system is great and definitely a better choice than the old Diablo 2 system, we can take tanking skills to fight a boss and then retake our usual grinding or “fun” skills/runes.
We can change tactics, for example for the barbarian class. We can play with a 2 handed weapon or with 1 handed weapon and shield. Some skills/runes are designed to increase your attack speed, gain health after you hit so the 1 handed weapon version of the barbarian can use this tactic unlike the 2 handed barbarian that should use knock back from bash and earth shock.
Its like we can compare the blademaster with the tauren chieftain from Warcraft 3.
Diablo 3 is taking us through all the possible environments, dark fantasy, desert, snow regions etc. We have some long dungeons, some fun moments and dialogues.
Overall, Blizzard managed to create a great game and even more, they set a new example of how video games should be made.