I'm going to keep this very short. After playing this game for almost 100 hours, I can say that it is very realistic. I haven't played Multiplayer much though, if at all. Still need to get more into that part of the game, but playing alone with AIs isn't bad at all. Everyone is saying that the DLCs are overpriced, which in a sense is true, but you need to realize that this is a simulator, and not your casual War Thunder or whatever.

If you have lower-end pc, you should still be able to run this game, just fine, but it's likely that multiplayer wouldn't be possible.

You don't need TrackIR or anything like that even though it is very useful. I just learned to play without it and it is actually not bad. Even when I'm in a dogfight I can easily keep up, but sometimes it can get a bit chaotic.

If you are just beginning, I highly recommend you to buy the F/A-18C Hornet. It is by far the most user friendly high fidelity aircraft out there. It will take you sometime before you'll learn how to land on the carrier or how to drop bombs for example, but the learning curve isn't really steep. So in my opinion it is much more worth it, than buying the FC3 DLC.

That's it, I hope it make sense :D

Have a great day! :)