This was waved at me on Amazon Prime and was a wonderful treat to see.
I haven't seen the original 1970s series (though I dare say there are ways and means in the 21st century), so I don't have anything to compare this to but on its own.
Basic premise boils down to two boys meet a loveable little sea creature by the name of Sigmund (hence the title) and things basically boil down to their pulling out all the stops so that Sigmund (and the rest of his dysfunctional family) are not discovered by sea-monster obsessed Captain Barnabus.
Sigmund himself is ridiculously adorable (when the whole suspension of disbelief thing has done its job for a while) and the show therefore should have lasted longer than seven episodes. But on a positive note, its nice to see actual physical costumes for something like this - it would be so easy to CGI Sigmund, his family (and most things here actually) so kudos for that.