We used to have a recumbent tandem (as well as two upright tandems, over the years). It was a blast to ride with a couple of caveats:

1. VERY VERY slow up hills, even for strong riders. This tends to be true of recumbents in general as they are typically heavier than upright bikes and you can't stand and power over hills. Small "tandem rollers" can be quite fast on an upright tandem, but there's really no such thing on a recumbent tandem.

2. Depending on what kind of tandem it is, it can be extremely long and cumbersome. Ours was the longest type (long wheelbase with under-seat steering), which made it 10' long. Try doing a u-turn with it, or transporting it to an event. We actually had it made with s-and-s couplers for travel, but rarely used them as they were time-consuming to deal with too.

We ended up selling it back to the dealer (Larry Black in Maryland, who specializes in tandems, recumbents, and other "funny" bikes) and getting an upright tandem instead. (And that didn't work out either, but for other reasons -- like others have said here, I couldn't give up control and the ability to see in front of me, brake, shift, etc.)

Tandems can be fun but are definitely not for everyone!