Yup, it is fun. It's basically IL-2 in the Pacific, as it uses much the same game engine as IL-2 (the vast majority of content from Pacific Fighters is in fact included in the IL-2 1946 version incidentally, although there is less emphasis on purely that conflict). Pacific Fighters runs very well on a modest computer too, since much of the terrain below you is simply a flat expanse of sea. Obviously it has more appeal if you like naval stuff, since you can fly torpedo bombers and such, it even lets you recreate the attack on Pearl Harbor, although there are many options to fly from land bases too (more on this later).
Not got many screenshots from it, but here is one, ignore the silly captions on it and it will give you a good idea of the graphic detail in the sim, which as you can see, is pretty good, in case you are curious, that picture was done as a mickey-take of Silent Hunter 4, before it got patched.
Some things to be aware of: IL-2 (and hence Pacific Fighters) has a fairly realistic flight model, and this means that on realistic settings (which you'll be pleased to know you can turn on gradually via many options settings) it can be tricky to fly the thing, as you have to contend with things such as the massive torque from the engines of the fighter aircraft, an effect which will make the thing want to turn slightly all the time and roll a bit too. To counteract this you need to constantly apply some stick and rudder, or 'trim' it out with the rudder and aileron trim tab controls, so, if you have it in mind to use realistic settings, a decent joystick with plenty of buttons will help, as you can assign such controls to these buttons, which makes it easier to use than to have to remember a lot of keys (something which is not helpful when beginning). Of course, as I already mentioned, you can turn a lot of these settings off if you like, making it much more like an arcade flight simulator than a more realistic one if you choose, so in that sense, it is a good one to learn on, as realism can be gradually introduced when you get to grips with the concepts.
One tricky thing to bear in mind: Many of the aircraft (and a lot of the missions) involve flying from carriers and landing on them too (not all of them). Needless to say, this is a tad trickier than landing on a piece of tarmac several thousand feet long, as you do in a land-based aircraft. Navy 'pilots' call themselves 'aviators', which they claim 'are better than pilots', and this claim is somewhat justified, as a landing on a carrier is barely much more than a 'controlled crash' in some respects. So there's definitely some challenges to be met in Pacific Fighters, but these can be met gradually, since not all the aircraft are naval ones, you can fly a campaign in a P-39 Airacobra for example.
There are many choices of aircraft to fly, some that do not show up in other sims, so it offers a lot of variety, lots of bombers and fighters from Japan, the US and the UK, including unusual things such as the Seafire (the navalised version of the Spitfire).
It offers a lot of variety in terms of how you like to fight too. Typical American carrier-based fighter planes were big and heavy with a powerful radial engine, which made them better suited to fast slashing attacks than dogfights of the 'circling round and around' variety, whereas Japanese carrier-based fighter aircraft tended to be much lighter, making them suitable for a 'turning fight'. This is also why you see a lot of pictures of Japanese aircraft in WW2 going up like a roman candle, as they had very light armor and often were not fitted with self-sealing gas tanks (these being where the fuel leaking out from a bullet hole would react with a rubberised coating on the gas tank, melt, and seal the hole up). Like this (this is me zapping a Mitsubishi A6M 'Zero' in my Curtiss P-40):
I'd recommend it, and if you get stuck with learning how to fly it, post in here and I'll give you some tips, as I'm sure everyone else will too.
Chock