Does the samsung "battery life extender" work?

Solution 1:

The short answer is Yes, it will extend the battery life.
Can't exactly tell How much will it extend your battery life. But according to my findings and some research papers it should roughly double the life.

As your device uses a Li-Po (Lithium Polymer) battery, the word “polymer” has been used as promotional hype and otherwise it is almost similar to standard Li-ion. So everything that applies to Li-ion also applies to Li-Po.

A study* claims that overcharging by 0.01V reduced the life of an Li-Ion accumulator by more than 50%. The conclusion was that by reducing the charging to 80% of the full capacity you can prolong the life of accumulator very significantly.

Most Li-ions are charged to 4.20 V/cell and every reduction of 0.10 V/cell is said to double cycle life.
For example, a lithium-ion cell charged to 4.20 V/cell typically delivers 300–500 cycles. If charged to only 4.10 V/cell, the life can be prolonged to 600–1,000 cycles; 4.00 V/cell should deliver 1,200–2,000 and 3.90 V/cell 2,400–4,000 cycles.

It is sure that a Partial Charge is always better than a Full charge for a Li-ion. And a partial recharge will prolong the battery life.

A helpful chart about - How to Charge - When to Charge
_{* K. Asakuraa, M. Shimomurab, Т. Shodai, "Study of life evaluation methods for Li-ion batteries for backup applications", Journal of Power Source, 2003, PDF: http://144.206.159.178/ft/641/92454/1607542.pdf}