I teach piano and am using this book for my students who approximately grade 1-2 standard. It will take them a few weeks to learn one piece. Each piece is 2-3 pages long. Some of the adaptations are better than the others, but at least this book gives a piano student an opportunity to learn some fun music at a relatively early grade. The pieces are all in simple key signatures (maximum 2 sharps/flats).
I have purchased many of the books in the Really Easy Piano series and find them to be generally good value for money and suitable for students of all ages at the early grades. If you are deliberating which one to buy and you don't have a teacher like me who has a lot of them that you can view, then see if you can find out what songs are in the books and pick one with songs that you are interested in learning. That is the one disappointing thing with buying manuscript from Amazon - you can't see the list of pieces before you buy the book!
New Chart Hits contains the following pieces: Broken Strings - James Morrison and Nelly Furtado Better - Boyzone Chasing Pavements - Adele (NB this is not a great adaptation so I don't recommend that you buy this book only for this piece, as you might be disappointed) Greatest Day - Take That Hallelujah - Alexandra Burke Human - The Killers I Hate This Part - The Pussycat Dolls If I Were a Boy - Beyonce Issues - The Saturdays Just Dance - Lady GaGa Love Song - Sarah Bareilles The Man Who Can't Be Moved - Script Run - Leona Lewis Say (All I Need) - One Republic So What - Pink Take a Bow - Rihanna Viva La Vida - Coldplay Warwick Avenue - Duffy Closer - Ne-Yo