It works, but it is a bit of work.
a) in Lightroom you can't have smart collections which sync with Lightroom (online)
b) Portfolio does not update automatically from the collections which are sync'ed
It is especially b) I have a problem with, which also means that I do not do as much with Portfolio as I feel I should. But I'm using it as it's free (comes with the subscription) and it does just enough for me not to look else where.