Midway was good, but short, this is more of an excellent game, with more content. Very nice.
The shortness and map limitations have been addressed. The single player campaigns are longer. They don't follow a story about particular guys, its done more like a History Channel show, and I like that better.
There appear to have been some improvements in naval gunnery, that's a bit easier now, and ship-to-air AA is more effective as well. Air combat gam play seems to be about the same, except that you can choose a couple of different loadouts for each aircraft type, and can have a larger selection of aircraft to choose from at any given base or carrier.
The graphics are excellent. There are little sailors strolling around on the decks while bombs fall around them, and the damage to ships, along with smoke and explosion effects are awesome. There is something gratifying about letting loose a salvo of 16" shells at a destroyer and seeing it blow to pieces. Fun stuff.
Another thing missing from the first game that has shown up here is night and weather. That somewhat makes sense since historically, the major battles up to and including Midway were all during the day. The key battles near Guadalcanal were at night, and they have been nicely re-created here.
Overall this is an excellent game.