Philips Hue is an entire range of smart lighting products. Individual bulbs are $14.95, or you can get them in kits with different accessories (dimmers, or the bridge which acts as the heart of your home smart lighting).
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Pro Tons of utility and customization
Philips has released the Hue API, allowing individual developers to create their own apps that utilize the Hue bulbs. These apps are often more robust than Philips' own app, letting lights change color in sync with music, flickering whenever you get a tweet, or can change colors to reflect the stock market. The possibilities are nearly endless.
Pro Wide range of colors
The Hue app comes with default color pallets, but you can take control and customize the colors any way you want. The bulbs support up to 16 million different colors covering all areas of the spectrum.
Pro Supports IFTTT recipes
There are many fun IFTTT App Recipes that you can sync with your phone and Websites. If THIS happens then do THAT to the lights, i.e. IF your team scores a touchdown(ESPN), THEN turn the lights the color of your team.
Pro Compatible with Philips Ambilight TV
If you have a Philips Ambilight TV, you can hook your Hue lightbulbs up with the TV and the bulbs will change color with what is on the screen, making for a very immersive experience.
Con Requires a central hub
The Hue bulbs need to be connected to a hub which needs to be wired into your router. This adds another device to the mix, and also increases the cost (it's $60 on its own, but it is also included in some of the bundles).
Con Bulbs aren't super bright
The first gen bulbs (what are available right now) have a maximum brightness of 600 lumens - similar brightness to a 50-watt bulb. The second gen bulbs will have an increase to 800 lumens, which is in-line with the amount of light that 60-watt bulbs produces - however these aren't available quite yet.
Con Some colors can be difficult to create
Blue tones tend to come out purplish, and green tones tend to be more yellowy than they should be.