Disclosure
I received a set of Nitto Motivos as part of their tire sampling program. Part of the terms are that I post a review on various forums that I participate in, once upon installation and again after 3,000 miles.

Introduction
The Motivo was introduced in late 2011, is billed as an “all-season ultra high performance” tire and has a 60,000 mile limited treadware warranty. They seem to be receiving good reviews in the motoring press (Motor Trend, Road & Track, Tire Review) and user reviews (Mustang Forums, Club Lexus, Jaguar Forums)
Time to see how they do on my 2010 E550 coupe, which I bought in February as a CPO. It came with four new Pirelli PZero Nero all seasons (235/40R18 on the front, 255/35R18 on the back) and I've put about 6,000 miles on them in a wet and dry driving conditions, city and rural, low speeds and high speeds. I've found them to be fine - slipperier than I would like with plenty of wheel spin (yes, I know it is a 550…) and uneventful skidding on tight turns at speed. With that background, I was keen to take try the Nittos.

Let's Talk About Specs, Baby
Let's take a look at the specs for the 235/40R18. I'll add the Continental DWS for comparison (you'll see why later):

Nitto Motivo
Service description: 95W (1521lbs/168mph)
UTQG: 560A/A (higher is better)
Country of origin: Japan
Mileage warranty: 5 year/60,000
Street price: $135

Pirelli PZero Nero All Season
Service description: 95W (1521lbs/168mph)
UTQG: 400AA/A (higher is better)
Country of origin: Romania, Germany
Mileage warranty: Unlimited/45,000
Street price: $165

Continental DWS
Service description: 95Y (1521lbs/186mph)
UTQG: 540A/A (higher is better)
Country of origin: Mexico
Mileage warranty: 6 year/50,000
Street price: $200

The Pirellis are softer than the Contis or Nittos (400 vs 540 and 560) but have the better traction rating (AA vs. A), which is interesting given my experience with them.
I went to a local Discount Tire Company (who are a Nitto distributor) and had them installed. I took the opportunity to put new AMG wheels on since my car came with the standard wheels.

Installation







When they were installed, I asked the tech whether he'd had any experience with them but they're too new. He said that he'd also heard good things and they were being compared favorably to the Conti DWS, which I've had on previous cars and have liked.

Performance
How do they perform? Well after a week with them, they feel and sound better than the Pirellis. On the freeway, quick sound level measurements with an iPhone sound meter app indicate that the ambient noise is 5dBs quieter with the Motivos than with the Pirellis. The car feels more planted and grippier. Curves where I would have lost grip no longer do so and wheel spin is subjectively less.
The only issue I've had is that one tire triggered the TPMS but so far I'm putting that down to a combination of incorrect air pressure and incorrect recalibration of the TPMS.

Warranty
Nitto make a big deal out of their limited 60,000 mile treadwear warranty and claim “Longest treadwear warranty among all manufacturer published (as of May 2012) warranties for W & Y speed rated all-season ultra high performance tires.” It is certainly the best warranty by mileage and for me that's a winner, but if you're more concerned with duration (maybe your car is not a daily driver), Continental's warranty is a year longer and Pirelli's is unlimited. An important note on the Pirelli warranty is that if you have different sized tires on the front and back (staggered), the mileage warranty for the rear tires is half what is stated, so 45,000 for the front an 22,500 for the back.

Summing up
So far, the Motivos are very nice. If they're everything they claim to be, they'll be a winner.
More info to come as I live with them longer, but in the meantime I'll try to answer any questions.