Pro: They can help you with getting permits and they are all-in-one for some features you would expect. If you just need a fairly quick installation of a safe room for your family to evade a tornado or hurricane, these are probably the quickest path if you have $100+k laying around.
Con: They are super expensive and you are paying a premium for not getting a local engineer to draft a plan and custom build a solution for you. These pre-built containers are small and meant for short term usage. Their air filtration systems are extremely expensive and yet still noisy. Their generators are noisy and too close to the living quarters. They are not designed to protect against civil unrest, as attackers can block / lock you inside. They assume ground level is not a flood zone, so you have to ensure that all water will run past your hatch. I mention this because even their own videos show them building in flood zones. They have a ladder and hatch which is not compatible with the elderly. You need to plan in advance for conduits, welding and wiring for solar panels. The hatch is very small, which means equipment has to be broken down before installing or replacing. Adding things after the installation is completed may be problematic. Their sales people are very pushy and make aggressive videos trying to take down their competitors. Each claim to have a secret sauce which is a warning sign to me. This suggests they are not following best practices that military bunkers have used for many decades.
In my opinion, it might be better to research this well in advance and look into existing plans created by people that have built "earth ships" and other environmentally friendly geothermal optimized homes that are either partially or completely under ground. There are thousands of videos on youtube of people that have done this for about the same cost as these all-in-one solutions that provide more living space, storage space, less dependency on generators, and the list goes on. You may even be able to get a grant in some locations to offset the cost of an earth ship.