IMHO Mobil-1 used to be a quality synthetic (back in the days before Exxon and Mobil merged), and I would still (even now) classify it as an OK (if overpriced for what you get) synthetic oil.
However, ever since Exxon and Mobil merged, the Exxon execs have found ways to penny pinch on their products. And when it was discovered (by independent lab testing, reported over on the "Bob is the Oil Guy" forums) that XOM had changed the formula of Mobil-1 to use much cheaper ingredients in their flag-ship synthetic oil product, without telling anyone about this first (i.e. essentially giving you a less quality product for the same price and with the same name) I pretty much decided (then and there) to stop using the stuff.
As to the "Advanced Fuel Economy" link you provided, it looks like it is simply a marketing ploy to sell their "0w" versions of their synthetic engine oils. And while they are correct that a "0w" oil (the first "cold weight" number before the "w" being a 0, instead of the more traditional 5 or 10) will save a little fuel (as well as a little engine wear) until the car fully warms up (after the car is fully warmed up, the 2nd number comes into play, and the 0w no longer matters), that fact is true of virtually all decent synthetic 0w oils (not just Mobil-1).
So if you want a good synthetic 0w30 (to replace the 5w30 or 10w30 you have been using), or a good synthetic 0w20 (to replace a 5w20 you may have been using), by all means go for it (I use both quality synthetic 0w20 and 0w30 in my cars, for example). However, I personally wouldn't fall into the marketing hype that Mobil-1 makes a better 0w30 (or 0w20) than any other synthetic oil maker. Instead, I would either go with a cheaper 0w synthetic (maybe the Walmart synthetic brand?) if you want decent quality at a lower price, or (do as I do) and go with a high end 0w synthetic oil that will safely give good performance for longer oil change intervals.
NOTE: I'm currently buying/using high end 0w20 and 0w30 oils from Amsoil (because I both like the lab numbers that I've seen when those oils were tested, and I also like my real world experiences as to how well those oils perform). And while Amsoil's "retail prices" (that you see on their web site) are a bit high IMHO, their discounted prices (PM if you want discounts on Amsoil products, as I took the trouble to become an Amsoil dealer a while back) are only a little higher than say Mobil-1 prices (while still showing much better lab numbers than Mobil-1 IMHO). OTOH I haven't seen the lab numbers on their newest "Advanced Fuel Economy" oils so YMMV, but given XOM's history of designing for cheap ingredients (and then trying to convince the consumers that you are so great by big marketing/advertising campaigns), I personally wouldn't expect their new "Mobil-1" lineup to be any better (quality wise) than their other Mobil-1 synthetic oils...
At BITOG when I looked at it there was mention that Mobil-1 fomula was switched.
Does that mean that the road test that BITOG guys did on it is void now? It was like a year long test without oil change, to see how it breaks down.