The bike without the battery is noticeably heavier and more cumbersome than a normal bike, but the bike with the battery... gee whiz. It feels very sluggish and also has a little tendency to tip to one side. That factor can probably be countered by putting on a second battery pack for longer travel times, better balance, and golly gee, even more weight. Those batteries are startlingly dense, and I'm not exactly a battery novice here.
However, I don't think a second battery will fit in, because when I tried to put the first battery on the other side, it didn't fit. It seems like the brackets are bent as it came to me. It's hard to be 100% sure because at first I thought maybe they were that way on purpose. Nothing in the manual or the pictures online gives me a clear enough view to say whether those brackets are supposed to be straight or not. So I'm going to send the enclosed picture to the manufacturer. If it is bent, I hope it's something I can replace at home, because sending the whole thing back is going to be a pain. But at least I'll be able to use both sides and maybe get a second battery, though I don't know if I'll ever need that much range.
The good news is the engine is powerful enough to pull the bike and me without any help up the hill of my road, which is the steepest hill I deal with, though not very quickly. On the not-as-steep, but much longer and more exhausting, hill leading to my mailbox, it can keep me going at a good pace by itself. And when it's running, I can pedal to add a little more without it being hard going; the transmission is good at combining my work and the engine's without me feeling like I'm fighting the engine. So it gets the job done.
I don't think I'd want to use this for exercise riding, though, or for riding for fun. It'd be great for riding whose sole purpose is to get to point B, or to exercise the dog, which is the whole point. But I'll be keeping my other bike. (Which means I need to find more room in the garage, which was already pretty full before I put in a snowthrower last week. Maybe I should bite the bullet and buy a shed.)
Tonight will be the first time taking Socks out with it.