Delta, which recently made a big change in how Skymiles are earned on flights, has made some little changes and one big one in how Skymiles can be used for flying in a new award chart that takes effect in 2015. The one big change is that members will now be able to book one-way awards for half the round trip; previously trips could be priced that way, but you had to buy a pair.
Delta says that 95% of the 44 changes are to require fewer miles. You won't see serious drops in the Award Chart: for both economy and business/first awards, almost all of the drops are in the upper levels. The three old levels (saver/standard/peak) have become Levels 1, 3 and 5; most of the price drops are in Level 5. There are also two new levels (2 and 4). From Delta, here are the DETAILS