Chris, my wife and I have about 3000 miles on our Bike E E2, including two trips across Iowa (RAGBRAI). We think it is an outstanding value and good performer.
We like the seats, in fact I prefer the Bike E Sweet Seat to the Rans seat on my Trek R200. We somehow had one "good seat" and one "bad seat". The good ones have back struts pinched at the weld, the bad ones have tiny tack welds on the round tube. The bad one broke but was easily pinched and welded.
We sometimes struggle with stability at very low speed, but that may have something to do with weight distribution since my somewhat tall wife sits almost directly over the rear axle. We even find that she can do a surprising amount of "steering" at low speed. Stability at 10mph and up is always superb.
The stock brakes were terrible, sort of like "suggesting" the bike slow down. I also felt the stock wheels were a bit weak for a tandem, especially a recumbent where you can't unweight the bike over large bumps. We upgraded to 32 spoke wheels and BB7 203mm disc brakes and now the brakes inspire confidence. They're easily modulated but have the power to lock either tire with on finger.
I upgraded to a bent, top load stem to bring my handlebars a bit closer to me, but that's a personal preference. This seemed to help our low speed stability a bit, but I'm not sure if it's due to the bars being closer, slightly wider or a combination.
We also felt like rough surfaces robbed us of momentum, especially the wooden bridges on our local bike paths. Schwalbe Big Apple tires have helped that tremendously by absorbing the bumps rather than bouncing the whole bike up and down. We haven't noticed any drop in performance on smooth roads.
The E2 is short enough to fit some "standard" bike racks and it fits easily on one across the back of our van. For some people this ease of transportation may be a very important aspect. For us it's certainly a convenience. The short wheelbase also lets us make sharper turns in tight quarters.
Over the winter I may switch to 175mm cranks because the recumbent position doesn't seem to promote the high cadence I'm used to on upright bikes.
If you have any specific questions don't hesitate to ask.
Tom Gentry
Life is too short for boring rides.