Ok so they are:
1. adding more bar and patio areas, and
2. eliminating that awkward gap between the OF fence and the OF seats. In some cases this is done by bringing the seats to the wall, in other instances this is done by raising the bullpen area to meet the seats.
I think these are going to be great changes. The Rockies added a bunch of bar/patio areas and it was very popular. It's a place for casual fans (aka girls and the guys who follow them) to go and drink in the summertime. It also improves the aesthetics of the stadium. At times, the stadium always kind of looked similar to Oakland Coliseum with that stupid gap. Third, it brings the OF seats closer to the action.