There are a number of new things that really grab my attention in AH3. First, the graphics are a major improvement over AH2. Secondly, having new fields is a nice breath of fresh air.
I'm also digging how well gv's can hide under the tree canopy. A single gv can really throw base defenders in to a panic. The Storch has become all that much more important.
The strat targets all prove to be more challenging to bomber pilots, there isn't a square box to plan on for a target. Everything is spread out and somewhat integrated in to other nearby buildings.
Having more gv spawn points in to the strat targets is nice too. Oh, and the ability for a wild weasel to go in first and knock out an ack tower then have the jabos such as Mossi's, 110's, Typhoons, etc, follow in behind is very nice. In AH2, that was an automatic suicide thanks to the auto ack.
Lots of new things in AH3. Good stuff.