From: Connecticut, USA
It depends on what you are looking for. WPO is primarily a strategic game employing World War I technology in the World War II Pacific Theater. That means your number of aircraft, as well as their ranges, will be significantly less. The battleship is the major strategic asset in this game, though there is significant land combat as well. If you like ship to ship battles, you should definitely consider this game.
The engine is original WitP, not AE. One comment I've heard from other WitP players is they like the fact there is less micromanaging, which lets them focus more on strategy. You still need to supply your bases and such, but not to the degree I believe you do in WitP. Another difference I've heard is with the lower detection levels the oceans feel "bigger" if you get my drift.
The AI can be fun for a new player, and serves as a great means of learning the game. The farther into the game you go, the less active it gets. Once you get tired of that you really should consider PBEM - it is much more rewarding. Also, make sure you have the latest patch from Matrix, as well as Kirk's latest mod (currently Pandora's Box) to give you an additional scenario, as well as much better graphics and additional ship & aircraft classes. I should add that Kirk's graphic upgrades will also appear in the stock scenarios, so it ought to be downloaded.
The stock game gets a bit imbalanced by mid 1928. Also, if you play PBEM you almost have to establish "house rules" making all the Allied countries neutral, and not activated until Japan attacks them individually. Fortunately the game comes with a pretty easy to use database and scenario editors, which can overcome these issues. I've never used such editors before, yet even I was able to do it. The user content added via editors are what has kept WPO alive for the past 10 years.
Many WPO players started out as WitP players. Some play it occasionally, others more so. I guess its a matter of personal taste. You'll be able to pick it up faster if you've played WitP, but yes, it is definitely a different game.