Yes and no. Wine clubs with introductory offers believe that if they can get you to sign up for their service, you’ll stick around long enough for them to recoup the cost of the up-front discount or bonus gifts and bottles. Generally speaking, if you’re getting a discount off your first box, yes the introductory offer is a great way to test out a service before committing to full price.
If the introductory offer is a heavily-discounted case (or six-pack) of wine, I’d say the introductory offer is only worth it if you like the wine. In many cases the wine clubs cherry-pick the selection for those introductory cases to encourage a second shipment which might be sub-standard.
I do not think bonus gifts are ever a worthwhile introductory offer — the freebies are always cheaper and inferior products whether they’re wine or wine accessories.