Here is an image of the two books, the one on the right being the first book I started with 'Elementary Korean' and the second is 'Continuing Korean' (though I am sure you can find it available with a much more fancy cover much like the 1st book). I am not going to lie to you, both books are very expensive, the first being £30-£40 depending where you find it online and the second is so far £40-£60 (these are second hand prices I am talking about, new copies add around £20 to those amounts). One tip I do have if you want to find these books cheaper is to look on abebooks.com or to look online at the times when students at University will not be buying these books. At University we have to buy the first book around September/October whilst the second in December/January. Friends of mine bought both textbooks for much cheaper outside these times due to no other students hunting for them so that is something I definitely recommend. 

Despite me already telling you about how expensive they are, I have to say both books are worth the money. I have yet to find a book in English that covers the Korean Language so in depth and well. It gives you dialogues, vocabulary lists and a large amount of grammar information per chapter. In class we cover about one chapter every 2/3 lessons, and the grammar can be a lot to take in, but if you study by yourself of course you can take your own time trying to understand everything. It is all well set out, and has a good index. There is also every 5 chapters a review chapter that sums up everything you have left so far, which is amazing for revision. In class we use every 5 chapters for the point to have a review test just to see how well we are doing and I find these extra chapters really handy in preparing for these tests. Another good inclusion is that you get a useful audio CD with different examples and dialogues, but also you have the rights to access the website connected to the textbook which has more activities and tasks which can aid in your studying progress. 

I may sound bias because Jae-Hoon Yeon is my 선생님 (teacher) at University but I am being honest in saying you will not find any better textbook with English commentary that are for beginners. I haven't been able to find one so comprehensive and useful, mostly relying before on Japanese books that teach Korean instead.

Another positive thing is 'Elementary Korean' has its own workbook which is entirely affordable  It's really handy in that it has a lot of tasks and extra work that can aid your studying because practice and repeat is the best way to remember and understand.

Overall for a beginner, these two textbooks are the best you can get, and I would struggle to find one that matches so well! I have other books I use but I will include them in later posts due to them being suited for so many different aspects of learning Korean. Remember if you have any questions, do not hesitate to drop me a comment on this post!