You can swoop until you have no ki if you want but you should really keep yur head above water when it comes to energy. If you get down to no ki and your opponent has any left he'll take you down.
After images are great, advanced melee w/Anims is great, Canyon is great, all of the other new maps are great, Gen ball is great, less super-powered Buu is great, combos are great, new explosions are really great, even simple melee is great. It isn't like I'm not already playing, but if I had to pick one anyway I'd say the new explosions.