I recently purchased a 1 year membership since there was a discount til May 31. There is currently only 1 location open located in Menlo Park, CA which is about 20-30 minutes drive from my house. They said in about 2-3 months other locations will be opening like in Sunnyvale, CA which will be closer to me. I have already attended their Basic Usage and Safety classes (extra fee) for Mill, Lathe, Mig welding, and CNC Plasma which is required for some machines before you can use them. They also require you to sign a release and waiver form. So, as far as the liability, the required courses and waiver form takes care of that. They just bought a new large commercial CNC mill to be used for only 2-D wood projects (no metal projects).
The main limitations I see is that their large Bridgeport style mills are all manual (no CNC), but have a 2 axis DRO on them. Their lathes are all manual (no CNC). They do have 2 smaller CNC mills, but are not meant for heavy machining and have a small spindle motor like a trim router motor and they are the techoIsol brand. I will have to wait and see what kind of equipment their Sunnyvale office will have. Also, the membership is specific to a TechShop location, but you can transfer your membership from one location to another.