I have a Slipstream and I'm a seasoned DF rider. I can say first-hand it takes time getting used to the "feeling" of a recumbent. The physics are the same but the configuration makes everything you've learned to expect come from new directions. For example, gravity is felt in front and below you on a DF but on a recumbent it's now behind and below you. The long wheelbase makes turning a new experience and when you stop, you are not poised to take a standing posture. On the Slipstream you bend your legs at the knee and put your feet on the ground but most of the weight is directly below your butt so a bit of extra effort from your legs is needed until you get used to the new sense of balance (stopped). Turning takes more of a conscious effort since you're sitting in a chair instead of balancing on a saddle and can simply lean to turn. The chair makes you forget to lean into turns it seems. At least that's my experience.

But in spite of all this, the recumbent is a pure joy to ride.

I've tried a trike (Catrike Expedition) and the first thing I noticed was no leaning at all. This feels weird in turns and you have centrifugal force to deal with if you're turning a tight corner at speed. The other thing I noticed is a rougher ride with three wheels picking up the road bumps instead of two. On the Slipstream you literally feel like you're riding a hammock on wheels. I suppose they all have their pros and cons but recumbents in general are a lot of fun.