is this insulation good for side of shipping container?

Summer or winter?

Reflective bubble wrap can be quite effective for improving personal comfort and reducing heat inflow if installed correctly. Not sure about the longevity of the particular product linked, or the practicality of fixing it in place with appropriate air gaps.

Semi-rigid foam insulation with reflective foil such as the EPE sheet from the same site is probably going to be a lot easier to deploy and likely to stay in-place (and therefore be effective) over a longer period.

Note that the EPE (expanded polyethylene) core is likely flammable - it is the same core material used in flammable building cladding. A foamed or expanded polypropylene cored material (if available) would be self extinguishing. Polypropylene is slightly more expensive than polyethylene, which is why it isn't used in the cheapest materials.

My main concern about a low cost product intended for single use (e.g. food transport) is how long before the plastic starts to disintegrate, not its comparative insulating performance. No matter who makes it metalised bubble wrap is only going to have a modest R-value, maxing out at around 1.0 if carefully installed with appropriate air gaps. For anything other than a temporary application it would be better to buy a building grade product like Polyair from Bradford or Polycell from Sisalation.

Nevertheless a reflective sheet will reduce the amount of radiant heat waves from the hot surfaces it covers, and can make the room feel less hot even if the air temperature is not reduced by a huge amount. A product with an expanded foam core can achieve a higher summer (radiant) R-value, almost double depending on circumstances, but is going to cost more.

Edit: The product linked in post #1 is sold as home insulation, but I'd still be concerned about the longevity of a low-cost product compared to the industry standards, and the ease of effective installation that actually achieves optimum performance.