May i try to offer a little different opinion? I would rather suggest you to pick the UML distilled book again and try to read it on some lazy relaxed sunday, and maybe your opinion of the book 'll change.
I found the UML Distilled breeze to read and understand. I have read Head first design
patterns as well, and it was similar experience as UML distilled (but more fun), won't feel like putting down the book before finishing whole of it. The other UML related books that i know about are either too verbose, focused on process/tool/programming language, or skip important stuff (i am not saying there aren't other good UML books out there -- i just don't know about any other low_fat_and_lucid book suitable for introduction)