I have the Saris Bones 2. It's an aesthetically appealing trunk rank with a lifetime warranty. It has worked absolutely perfectly for me without a problem for two years. It fit fine on my 4-door Focus and then I bought a hatchback Mazda 3 with a spoiler. My spoiler does not have a gap between the spoiler and the car, so I was in the unfortunate position of running the straps over the top of the spoiler. This made me rather uncomfortable, but I had a friend who is a mechanic take a look at it and he said to me that most of the weight presses down into the trunk, not pulling from the straps. It's been 18 months on this car and my spoiler hasn't detached yet.
With the Bones on, the rear door is heavy. I have to carefully hold it while closing it or it comes down with a bit of a bang.
I cannot use my rear wiper with the rack on. In fact it's stuck open right now because a designated driver accidentally bumped the rear wiper button.
For most FS bikes, you'll have to buy a $40 adapter to use with the rack, but I imagine that's true of all racks of this type.
I'm am completely and 100% satisfied with the Saris Bones 2 rack. However, if I could go back and do it again I would get a roof rack and/or a hitch rack. Both of those options are more expensive though, as my car doesn't have roof rails or a hitch, so I'd have to have them installed. I want a roof rack in addition to, not to the exclusion of, the Saris Bones. That way I can haul 4 bikes instead of 2.
Why would I rather have a hitch rack given the option? It's not a trunk, it's a door and it doesn't work as gracefully with the rack installed. I can't remove the rack easily. I can't use my rear wiper.
I'll upload a picture of how I have it installed so you can get an idea of how it be on your car.