The LS has its pros and cons.
Yes it gets bad gas mileage but its a luxury performance rwd sedan. The V8 and V6 get similar mileage. The back sucks indeed and its very cramped but the seats are comfortable. The difference between a full tank of regular vs premium is what $5? Not enough to bitch about. No matter what you will pay over $50 to fill any car up with todays fuel prices.
Front seats are even better and very spacious...im a big guy at 6feet and 260 pounds and i have plenty of room. A black on black LS with some nice wheels will get plenty of stares.
Aftermarket is very limited but we get very creative over there. The tranny can be built up as its the same as the 05+ mustangs. And theres several intake and exhaust options.
As far as reliability, its all about replacing what hasnt been replaced before. The coils/plugs once replaced will last a very long time granted the gaskets are good.
The cooling system is pressurized and parts will need to be replaced. But once replaced again they will last a long time.
In my two years i have not had any serious issues and have only done routine maintenance. Its at 75K and runs very well. Oil always comes out clean and all i have replaced are theromstat, belt, pulley, tensioner, coils, plugs. Battery and tires were replaced because they were still original from factory when i bought the car. Brakes were done also but again routine stuff.
And LS's can come with factory HID's which are sweet. The engine is a small V8 but it has a good amount of power and it is still a DOHC 32V with 280 crank HP. Sure we would have liked a 4.6 mod motor but it is what it is. I can still drive like a douche and run low 15's all day long.
Again we did not buy our LS's becuase they have four doors. If they were made in a 2 door i would have bought it instead. They are just downright sexy vehicles. Dont let the V6 base LS's on 16" stock wheels that are all beatup and driven by old people distort the beauty of these cars.
And yes they look like BMW's because they were designed by a German guy as a direct competitor to the 5 series.