I have a 2012 Twist Esprit Power, but the man's version - as you say, much of the spec is unchanged - the most visible difference is that mine has a horizontal battery on the top of the rack, whereas the 2011 has the vertical mount.
I've done 2500 miles on mine and the only problem I've had has been two broken spokes on the back wheel - easily fixed, happens to most bikes, and I'm no lightweight plus I carry heavy panniers.
I upgraded the brakes to Shimano Deore, because I found the originals to be very weak, especially given the weight of the bike - but you might find it's enough just to put better-quality brake blocks in.
Other than that it's been rock solid - very well built, and no sign of corrosion anywhere despite riding it along the seafront in all weathers. The 7-speed hub has been faultless. The ride is supremely comfortable; the forks seem to be decent quality.
Performance I find to be fine but I use it on the high setting all the time; I easily do a 20-mile return trip on about half the charge. It tops out between 15 and 16mph but the cut off is very gradual so it's easy to ride around that speed. I'm a reasonably fit person and I cycled before I bought this - I often go quicker on the conventional bike, but the Giant is more consistent.
Do test ride it though; this bike doesn't have a throttle (despite its name), and uses a torque-sensor in the cranks. It works very well indeed, feels very natural, but can give the pedals a mushy feel - it is NOT a bike you want to be riding without power.
The only reservation that remains for me is that Giant doesn't like to publish technical data; I haven't sought any detailed answers yet, but there's a possibility you'll find yourself locked into Giant dealerships and having to buy a replacement battery at their price. Others might know different though.
(They don't seem to do the £999 bike now - the cheapest list price is £1199, and yes that does have derailleurs plus a 36v battery - the old £999 bike only had a 26v)
