Softenni is known as a lolicon show. The series itself was really not particularly extreme, except for some silly and predictable fanservice. (Nobody cares about seeing pantsu but whatever.)
These specials throw it all out there. Do you want to see 13-15 year-old naked anime girls? Here you go. Uncensored.
In terms of quality they're quite good. If you enjoyed the series then absolutely give these specials a watch. It's the same humor and not just throwaway trash.
But, if you are uncomfortable with the 100% nudity plus lolicon, and have concerns in that regard, I do not recommend these videos.