In Diablo 2 there were a number of ways to make life much more difficult on yourself if you made the wrong choices on the skill tree. The skill tree is gone and it seems that changing between "builds" will be very easy to accomplish.
Are there any choices that can be made early on that will make the game particularly difficult?
Conversely are there any builds that seem to be particularly strong for getting up to the Skeleton King?
For example if using a ranged demon hunter does the lack of a shield strongly handicap you? Are there creatures that could close too quickly to avoid taking a lot of damage?
If playing a melee demon hunter, does the available skill options work against you even though you have higher defence?