I'm moving to Finland for school, and intend on living there for a while.. Beginner's Finnish has been an AWESOME tool for the crazy grammatical rules and conjugations that Finnish requires you to learn. Lots of dialogues you can read, with phrases and useful sayings as well. The vocabulary is not extremely extensive, but has plenty to learn for beginners. I would dare say almost all the grammatical rules are in this book.. but I could be wrong.. there's enough to keep you busy for a real long time. I would suggest buying a finnish-english dictionary along with this book to keep up the vocabulary.
I got this book and "Finnish An Essential Grammar" by Fred Karlsson, and this is the better book in my opinion, but using both together has been very beneficial.. like I said, I've used Beginner's Finnish way more than Fred Karlsson's book.