I'll go into my major beefs with Mixbooks below.
Fuzzy Previews in Web AppMix books allows very large, high resolution images, I imagine there is an upper limit, but I haven't found it yet, even after using a 13 image pano from raw, a very large image. That's good.
What isn't so good is that it uses a relatively low-rez and apparently fixed size preview for rendering the previews that are used to create the book. This causes near panic in everyone who sees a big two page spread as a fuzzy, grainy mess, that desperately needs to be fixed. From experience, I know that pages like this will print just fine, but they look horrible, set off alarm bells and generally lead to a gut check when hitting that final button which is only relieved when the finished book arrives.
This problem could be avoided if Mixbooks would generate a better preview for large images, like page spanners, for use in the GUI. Alternatively, a notice that the actual image is sharp overlaid on the fuzzy preview could suffice.
No Automatic Page NumbersAdding page numbers is a pain in Mixbooks.
My earlier books were created using Apple's Aperture software. With Aperture I would click a few boxes and page numbers would appear on each page in the position I indicated. They were correct and automatic did I mention they were correct?
Mix books has a help page on how to add page numbers. It amounts to placing a text block on a page, position it where you want, type in the number you want, repeat this for every page and change it when you move pages around. The result is keeping numbers aligned and correct is very challenging.
No Bleed Warnings for ImagesI often have images positioned to "bleed" off the page, that is extend to or beyond the edge of the page on one or more edges. If an image isn't a "bleed" I like to leave a consistent border of background or white around all of the edges.
This seems to be easy to do in Mixbooks, especially since it's composition tool shows what looks like (but isn't) a preview of the printed page. The problem is the creation interface is guessing at the actual page borders. When the book goes to print there is some margin for error and some of that margin is beyond the displayed page area.
This means a perfectly positioned image, hard up against the preview edge, may print with a sliver of background between it and the page edge. This is impossible to see in the preview and wrecks many bleed images. The workaround is to assure that bleed images go safely past the edge of the page, which has to be done very manually on each image and is difficult to check.
Odd Gutter Behavior for Page Spanning ImagesImages can be set to span pages. This is a good thing. Unfortunately, some images set to span pages leave white gap on one side of the gutter interrupting the image. The workaround is to be sure to not have page spanning turned on unless you really want it on an image. This is tricky to check for and needs to be handled on image insertion.
Difficulty Judging Font SizesI have a problem getting font sizes right. I like 11 point or larger fonts in the GUI but generally hate them on the printed page, they seem comical in printed books. This is despite my screen being large enough that I work on a preview that is as large or larger than my printed books.
The workaround is simple, use 10 point or smaller and trust they will look good printed.
Difficulty Aligning Images/Text with Small GapsGetting the gaps between pictures right is a challenge for me. I like small, uniform gaps. The GUI allows mouse dragging, which is very imprecise but does include snap to alignments so elements are easily left, right, center, top, bottom aligned. It also allows pictures, but not text to be "nudged" a small amount with the arrow keys. This makes tight alignment of images possible but text is restricted to drag and hope.
The GUI would be improved if a grid could be turned on and adjusted for alignment. I would set the grid to my desired spacing and things would be much easier.
Flaky Flickr ConnectionI tried using Flickr as a way point for my last creation. It really speed up the upload process. Lightroom can send images directly, quickly into Flickr. Mixbook can load images from Flickr very quickly. All of which speed things up and felt really good.
That is until my book started to lose images, finished pages sprouted ugly X symbols where my pictures once were with a small text saying the image was no longer available.
I think the problem was triggered by changes in Lightroom that were published to Flickr. Mixbook seemed to then get unhappy and drop the connection. Saying the image was no longer available, when in fact it had just been updated.
Mixbook could offer an option to sever the Flickr link when loading images into it's GUI. Or take some other action to avoid these nasty "X's." As it stands, this feature is far more dangerous than useful.
Page Sizes not as AdvertisedI ordered a hardback and layflat version of my latest book, in the landscape 8.5x11 inches size. I was a bit surprised when they arrived that they were obviously different sizes.
The plain hardback version had pages measuring 8.375 x 11 inches. The exterior measured 8.875 x 11.375 inches. Almost what I expected.
The lay flat version had pages measuring 8.062 x 10.5 inches. The exterior measured 8.5 x 10.75 inches. Noticeably smaller than the advertised page size. Certainly enough difference to create bleed and alignment problems.
Another difference, the lay flat pages are thick, really thick. The 93 page book in lay flat is 1 5/8" thick while the "normal" edition is closer to a 1/2". This results in a very unexpected and disappointing size for the layflat version. I definitely would not recommend this "premium" format.