Yeah, LFS is one of the best investment I made in terms of a game. I bought my license almost two years ago (wow time flies by...) and I never stopped enjoying it.
From what I have tried, it's the most realistic driving software. (more than Forza, the GT serie, etc).
The variety of cars is simply amazing. Sadly, it is not exhaustive yet, but i'm sure it will be. There are no karts at the moment, but you have the MRT which is the closest to a kart (it is a car made by the McGill racing team according to the FSAE serie specs, I'm sure you've heard of it
so it's more like a mini single-seater). You also have got several open wheelers with different power/handling ranges. Finally, the tin-top/GT selection is very diverse, providing different kind of fun when you want
.
There are no stockcars yet, but there is a tri-Oval track. The GTR cars seem to fit in perfectly to simulate stock car racing (especially the XRR that is a front-engined RWD with 490hp and 2200pounds).
There are lots of permanent servers that you can join which offer a very good support and racing. For the moment, I find the RSR and NDR servers pretty amazing ! You have Rallycross tracks, and support to make your own layouts (add objects to the tracks, so that you can build a rally track using the patches of dirt outside of the tracks). You can drift if you want as well and there are lots and lots of personnally owned drift servers. Some players like cruising (a kind of driving for fun game to unlock the cars - but it's just specific to these servers, otherwise you can drive any car you want on any trac you want at anytime you want
).
Trust me, for some dollars it's a great investment. Especially with the dollar/euro or dollar/pound exchange rate, you'll be really enjoying your product compared to the money spent