What are the pros and cons of lithium ion batteries (besides cost)? Answered

http://en.wikipedia.org/wiki/Lithium_ion_batteries

Pros:
- Wide variety of shapes and sizes
- Lighter than batteries of similar output
- More power at lower voltages
- No memory effect
- Lower self discharge rates

Cons:
- Short shelf life in some conditions
- Higher internal resistance
- Not as durable as other batteries