Yes, I'm also enjoying this sim very much and I certainly don't regret every cent that I spent on this sim/game!
IMO, the campaign (career) is extremelly well built with a very interesting story which is almost as good (again IMO) as the Operation Flashpoint Cold War Crysis campaign (which IMO was by far the best campaign that BIS ever made for their games). The Take on Helicopters campaign/career resembles very much to a "typical" RPG game where you have the main missions which are part of the story and when you end those missions the campaign/career will end (at least the story part) and just like in the RPG games you also have the "side missions" (which in ToH are missions offered by the "government" and "private contractors") where you can earn extra money which allows you to buy stuff like extra helicopters and equipment for the player's helicopters (such as recover winchs, cameras, FLIRs, etc...) and the great thing is that most of those "side missions" can be replayed (in order for the player to earn more money) and every time you replay on of those missions, that mission will be somehow diferent (such as diferent locations or even diferent kind of objectives). I just wished that there were more "side missions" and more types of these missions.
Despite having some issues, in general I do like the Flight model of this sim where like in a real helicopter you must always keep and eye on the Cyclic, the Collective and the Tail Rotor pedals all at the same time and despite that the trim will alleviate some workload on the controls but you still must constantly keep and eye and compensate all the 3 controls. So the flight model in Take on Helicopters is much more nearer to a "sim level" than to an "arcade level" and IMO it's way more realistic than many helicopter sims and/or dedicated helo games.
I just noticed that in order for the cyclic control to be much more realistic the player must reduce the Y axis sensitivity a lot from that comes originally (putting the Y axis sensitivity at around 25% works great for me) or else it will extremelly hard to put the helicopter on a hover (without using "auto-hover" of course).
Well, this is a small and resumed oppinion of mine about this sim after almost playing the entire campaign/career (which I haven't finish yet)