The good news - some are very reliable. I have five LED bulbs outside that have run dusk to dawn for two years with no problems.
The bad news - some bulbs are VERY unreliable. VERY high failure rates.
I purchased 12 LED bulbs (8.5W product 47856) from LEDLight.com and 7 have failed. To make matters worse they are refusing to replace them now.
Beware of LEDLight.com. This company is selling products that they know are defective. No support for failed LED bulbs. These bulbs are very expensive ($20 - $105) and in some cases last only two or three weeks. They refuse to replace defective bulbs. LEDLight.com is selling known defective products and has bad customer service.