I originally wrote from my iPad and I have a hard time using the touch keyboard.

Here's my 2 cents:

1) Cheaper than Adwords, much much cheaper. The ads tend to be expensive when you first get an estimate from Facebook, but in practice, this number goes down 5-fold. Also, in comparison to Adwords, it is at least 5-fold cheaper.

2) Easier to target people. This depends on what you are doing, but I believe it works better if you are trying to build a community with a specific interest. However, Adwords is probably better for targeting advertising for an e-commerce store.

3) If you advertise your fan page, you have a hook to constantly advertise to your fans. I like building my fan page, generating conversation, and sparking interest. It is important to give users good content, but it also doesn't hurt to self promote about 10-20% of the time. It all depends on what you are doing.