Here is my opinion. I loved the slip in sleeves. I did not have to trim the 6"x4" photos. The other sizes you see are 4"x3" and other pages have 4"x4" so their is minimal trimming of photos. You also use way less adhesive because you just slip in the photos and not adhere them to the page. I feel like anyone can do this type of scrapbooking. It was super simple and works up really fast. I did 24 pages total in the event!
I also tried out traditional scrap booking with the Project Life cards (again pre-cut to fit in the pockets) but this time I put them onto a red 12x12 card stock. This gave me a little more flexibility on layout. The first image I kind-of clustered them in the center of the page and added some a title from the Project Life accessory pack stick on letters
In this image below, I stuck with the traditional layout of two 4"x6" or 3 4"x4"'s. The only difference is that I trimmed the photos 1/4" inch so you can see some of the red card stock. These pages are 12"x12" red card stock with the images adhered to the pages. These are not slip in pages below.
