I have a Giant Lite (Uber Fred in my sig) and it's just had it's first birthday. The Giant comes in at 45 pounds, mine is almost 50 with the addition of the fenders, saddle, etc, and has nickel metal batteries. The Lite/Twist is no longer produced, which is a great shame. The major difference between it and most E-bikes is the motor is inline with the chain, not a hub motor, allowing a smaller motor the advantage of the gears.
Mine is a strict peddle activated drive (you have to pedal to make it go), and has 2 settings, regular and economy (75% power). Range is 30 miles if you are being conservative with the juice, and as little as 15 with a heavy load and full power, averaging 22 miles between battery swaps. It's not too heavy to pedal without assistance, but it's a heavy bike and you'll never forget to turn on the juice.
It rides almost identically to a moderately loaded touring bike, and is only twitchy when it's packed down.
I have 2 batteries with mine, one lives on the charger, the other the bike. Battery one has about 300 charge cycles (out of an estimated 500 cycle life span) on it and retains 80% of it's original performance. Battery two has about 300 cycles and has no discernible performance from new.
It's been through some heavy rain storms, many short showers and handled it well, nothing has died, and I spray it off at the carwash to clean it. It does have full fenders and mud flaps.
Ridiculously fun to ride, great town/utility bike, that can handle heavy loads with ease. I hate that it's going to have a life span now that it is no longer produced. Sooner or later something is going to break and I'll end up scavenging the frame.
If I have a load, this is the bike I grab. When my friends come over (even my bike geek friends) they always grab my giant to ride around.