Ranked in these QuestionsQuestion Ranking
Pro Very efficient
While any LED will be more efficient than incandescent bulbs, the Osram Lightify is one of the most efficient smart bulbs currently available, providing 89 lumens per watt (beating WeMo at 87, Philips Hue at 81, and GE Link at 78).
Pro Access to 2 major ecosystems
These bulbs aren't attached to their own proprietary ecosystem - they are built to be compatible with Wink and WeMo which are already established ecosystems which allow for third party automation as well as other features.
Pro Choice of hardware
Linked above is the classic bulb style, but Osram offers a few different products that fall into its Lightify family of products. These include an RGB flexible strip of LEDs (really cool desk/counter/home theatre accent lighting), and two other cheaper bulbs that don't offer RGB lighting (one has adjustable color temperature, the other doesn't).
Con Short lifespan
While virtually every other smart bulb is rated at 25,000 hours, the Osram Lightify is only rated at 20,000 hours. While it isn't certain these lights will clunk out before the others, it seems more likely.
Con Lacks polish
The app isn't as intuitive as the other higher-end competitors, and lights have a slight delay when turning on.