A resource for learning p-adic numbers

I'm looking for a good resource for learning p-adic numbers. I'm familiar with analysis, topology and overall with noncommutative algebra.

Fernando Gouvêa's $p$-adic Numbers: An Introduction is gentle and enticing. One of the most endearing books I've read.

The right book, of course, depends on your background.

"P-adic Analysis compared with Real," by Svetlana Katok is a very gentle introduction to p-adic numbers. This text is suitable for an undergrad who has taken some analysis and topology.

"A Course in p-adic analysis," by Alain Robert is a more terse and advanced book on the subject. It is nicely written as well, but it takes much more background to learn from the book.