The history of light beer is brief relative to other styles, and certainly less august. After a few fits and starts in the 1960s, Lite Beer from Miller struck the right chord in the 1970s and we have been burdened with this phenomenon since. Light beers are effectively a PR trick, not a beer; Miller, the first to actually sell the beer, did it through clever advertising ("Tastes great!" "Less filling!") Our sports events have been clogged with blights like Spuds MacKenzie and silver bullets ever since.
Of course, we've always had light-bodied, low-alcohol, low-calorie beer. In fact, the regular macros are pretty damned low-cal. A standard Bud or Coors clocks in at 150 calories, while their light version runs about 100. But draft Guinness has just 125 calories. Deschutes Cascade is 140. Widmer Hef is 159. (Buy low alcohol, light-colored beer, and you can be assured it's relatively low-cal.) The average man eats 2,500 calories a day--if he's putting away so many beers that he has to watch the difference between 125 and 150 calories, he's got a bigger problem than a beer gut.
And now we have Slim Chance, Redhook's entry into the low-cal sweepstakes. It's not the first craft-brewed light beer, nor even the first light ale. Hell, it's not even the first low-cal Redhook ale (Sunrye tips the scale at just six more calories than Slim Chance). It is, transparently, a market-driven lunge toward sales.
(We've recently been discussing what a "craft" beer is. I would argue this is a perfect example of what it's not. This beer's raison d'etre is commercial; nothing about it was "crafted," unless you mean by the marketers. That it comes from a craft brewery gives it no sufficient fig leafage, so far as I'm concerned.)
So how's the beer? Fine. It's professionally-made, reasonably drinkable, and actually pleasant. It's got just 3.9% alcohol but a noticeable 18 IBUs. There's a smattering of wheat, providing interest. It's lively on the tongue and easy to swallow. I'd certainly choose it over anything the macros are peddling. But it's not a high point of the brewers art, nor was it intended to be. It's a commercial product, period.
[Post slightly edited for clarity.]