Reddit reviews Functional Analysis: Introduction to Further Topics in Analysis (Princeton Lectures in Analysis) (Bk. 4)

You're welcome! You might also consider volume 3 and volume 4 of the analysis series by Stein and Shakarchi. There's also a great book by Tom Lindstrøm on the prerequisites to functional analysis, but it might be too basic for your needs.

I have a variety of books to recommend.
Brushing up on your foundations:
http://www.amazon.com/Beginning-Functional-Analysis-Karen-Saxe/dp/0387952241
If you get this from your library or browse inside of it and it seems easy there are then three books to look at:

1. http://www.amazon.com/Functional-Analysis-Introduction-Princeton-Lectures/dp/0691113874/ref=sr_1_4?s=books&ie=UTF8&qid=1368475848&sr=1-4&keywords=functional+analysis challenging exercises for sure.
   
2. http://www.amazon.com/Introductory-Functional-Analysis-Applications-Kreyszig/dp/0471504599/ref=sr_1_2?s=books&ie=UTF8&qid=1368475848&sr=1-2&keywords=functional+analysis (A great expositor)
   
3. Rudin's Functional Analysis (A challenging book for sure)
   
   More advanced level:
   
4. http://www.amazon.com/Functional-Analysis-Introduction-Graduate-Mathematics/dp/0821836463/ref=cm_cr_pr_product_top
   (An awesome book with exercise solutions that will really get you thinking)
   
   Working on this book and Rudin's (which has many exercise solutions available online is very helpful) would be a very strong advanced treatment before you go into the more specialized topics.
   
   The key to learning this sort of subject is to not delude yourself into thinking you understand things that you really don't. Leave your pride at the door and accept that the SUMS book may be the best starting point. Also remember to use the library at your institution, don't just buy all these books.