Why Led

Light Emitting Diodes (LEDs)
An LED lamp is a type of solid state lighting (SSL) that uses light-emitting diodes (LEDs) as the source of light, rather thanelectrical filaments, plasma (used in arc lamps such as fluorescent lamps) or gas.
LED lamps (also called LED bars or Illuminators) are usually clusters of LEDs in a suitable housing. They come in different shapes such as strips or on a PCB included in a Luminaire. There are also standard retrofit shapes available such as B22/E27 cap to retrofit Incandescent lamps or the MR16 retrofit Halogen lamps with a GU10 or GU5.3 bi-pin base.

To achieve the same brightness, LED consumes only 15% of electricity compared to incandescent lamp and 1/2 to CFL (Contact Fluorescent Lamp). This does not only mean a save of your power bill but also a substantial reduction of CO2 emission, which is your contribution to protect our globe.
Averagely, there will be 30 bulbs in a common family with the average power of 60w/bulb, and average usage of 3 hours/day.
Switching to LED, you will save your power bill by  more than $400 in one year.
Switching to LED, you will reduce CO2 emission by more than 200kg in one year.
Long-lasting :
LED bulbs last up to 25 to 50 times as long as incandescent, and 4 to 5 times of compact fluorescents. This can not only save your purchase cost but also reduce the risk of falling down when replacing bulbs. This is especially helpful for elders.
Instant Lighting:
Unlike CFL, which usually takes severy minutes to warm up, LED reaches its full brightness instantly after being switched on.
Enjoy the instant warm brightness of home and not to be annoyed by the slowly warming up anymore.
Compared to 85btu's/hour for incandescent bulbs and 30 btu's/hour for CFL, LEDs produce only 3.4 btu's/hour. This explaines why you will get burned when touching incandescent bulbs and CFL. Only if you don't hold LED bulbs for a long time, you won't get hurt.
This is especially safe for kids. Kids seem to have special interest in touching those bright bulbs.
CFLs contain mercury as vapor inside the glass tubing. Most CFLs contain 3–5 mg per bulb, with the bulbs labeled "eco-friendly" containing as little as 1 mg. Because mercury is poisonous, even these small amounts are a concern for landfills and waste incinerators where the mercury from lamps may be released and contribute to air and water pollution.
There is no mercury used during the whole manufacturing process of LED.
Comparing the features of LED, CFL & Incandescent bulbs.
  LEDs CFLs Incandescents
Frequent On/Off Cycling no effect shortens lifespan some effect
Turns on instantly yes slight delay yes
Durability durable fragile fragile
Heat Emitted low (3 btu's/hr) medium (30 btu's/hr) high (85 btu's/hr)
Sensitivity to temperature no yes some
Sensitivity to humidity no yes some
Hazardous Materials none 5 mg mercury/bulb none
Replacement frequency
(over 25k hours)
1 4 20+