There are several people here with real life racing experience, and I think all of them agree that LFS is very good. This is likely to improve with the impending patch. However, go on any forum and you will find real racing drivers preferring other sims. Why is this you ask?
Well, sim racing doesn't allow you to experience the forces acting on your body, and this is substituted by different things in different sims. Some one might feel that a particular way of doing something is better than another way. Want tends to happen I feel, however, is that people think the cars that are easiest to control in the sim must realistic, as driving in real life is easy. This is a mistake - if you could drive a real car without feeling any forces I bet it would be very difficult to control, and very easy to spin out.
Some 'sims' seem to boost the grip, or allow more longitudinal and lateral grip combined (so you can floor it out of corners with gay abandon) to compensate for the lack of feel. LFS doesn't do this (present tyres accepted). If you run out of grip capacity there's no 'extra' cushion of fake grip to help you. It's the reason why so many people love LFS, but it's also the reason people think it's like driving on ice (again, current tyres accepted).
If you get used to LFS (to the point where you can FEEL the tyres squirming, something NO OTHER sim attempts to recreate) then you'd be hard pushed to enjoy a current rival sim. If you give up before getting used to this you'll probably always prefer the less realistic but slightly more (initially) rewarding experience of other sims.
I've not done much driving of my F3 car yet, but the initial feeling is that LFS is very very good on most aspects. I await the new LFS patch, and more real F3 time, with baited breath. Other racing cars I have driven have been historic cars like Fulvia's, and they seem to have similar handing traits to the FWD cars in LFS, but as the age gap is huge a viable comparison isn't fair really.