TL/DR: Fun, fast, powerful, smooth, and quiet. Eats battery when pushed. Don’t toss your original yet.
For those still waiting for their Pluses, a quick review after a few days and several miles on mine (#7103):
A bit of background -- I live in NYC, bought my OW last fall, have put a few hundred miles on it on a mixture of urban and park riding. I've ridden pretty much all paved paths in Ft. Tryon and Inwood Hill parks, and many of the unpaved ones as well. If the weather is nice I take it on the last leg of my commute from Columbus Circle to my office on 63/Madison through Central Park. I consider myself an advance rider, have pushed my original up to 17.5 mph, take it just about everywhere, have ridden pretty steep hills. Fight the cabs in NYC traffic (with a helmet, of course).
Got my Plus on Tuesday, as expected (got a tracking notice when it shipped).
Out of the box -- very elegant looking, love the deck and grips. The first thing you'll notice when turning it on is the lack of noise. The thing is seriously quiet. Indoors, you'll hear the low humming, but on the street that noise fades into the background of the tire on the street. As you go faster, there is some noise, but when cruising down the sidewalk at moderate pace you feel like a ninja sneaking up on people. I always got "move asides" on the OW, not with the Plus.
People have mentioned differences in handling and acceleration. Besides the additional power, it seems pretty much the same. A slight lag in acceleration/deceleration perhaps, but not much. The power curve is smoother, but you still have the control you need to make pinpoint stops and turns.
But the speed --- very nice. I've always felt in that the OW was under-powered for NYC driving. Cars and even bikes tend to move 15-20 when moving, and I never felt I had the ability to accelerate out of issues. But the Plus is perfect. I've already hit 18.5, there's slight pushback at this speed, but now I feel like a first-class citizen in traffic, speed-wise. You get up there pretty quickly. On the OW I rarely got above 15 in normal driving -- with lots of engine noise. Now I blow past that regularly, and it seems controlled and comfortable. I don't feel that comfortable going much faster than that on unpredictable NYC pavement anyway, so props to FM on this.
There's a downside to this speed, however -- battery life. As far as I can tell, it's a pretty simple equation -- fast speeds will drain the battery faster, so clearly the high speeds have a cost.
Regarding new fancy full-pad footpads -- they look very nice, but I haven't noticed much difference. My stance isn't quite wide enough to engage the slope much, so ride-wise it seems about the same. I have noticed that accidental disengagements on idle seem to have gone down, thanks to the new sensors. I've read some complains of difficult with stops, but I use the heel-lift technique and it seems to work pretty much as before.
Is it worth it? Hard to answer regarding a $1400 purchase. I wanted a second one anyway to ride with my girlfriend and kids, so I was happy to get it. If I were able to sell my original for 80-90% of it's purchase price, I might be tempted, but otherwise I'd still enjoy my original even after having ridden the plus. As much of a dream the new one is to ride, it's definitely an incremental upgrade rather than a revolutionary one. I’ll still enjoy riding my original.