I am not sure if these comments would be considered simple or not and be cleaned up during production of the book, but thought it best to err on the side of caution just to be safe where all comments pertain to the Kindle version unless otherwise stated.
1. Web links are not functional and copy-and-pasting links includes book metadata for the Kindle version necessitating manually editing the link in the browser.
2. Text can be increased in size making it easy to read on a PC, Mac and Kindle, but the size of the figures seem to remain the same size making it difficult to see even on a 27" iMac to say nothing of a 7" Kindle for the Kindle version. For the PDF version the figures do seem to scale a little bit with the text, but in some cases it is still hard to see unless zoomed in quite a bit.
3. For the Kindle version text within the terminal figures are pixelated and sometimes hard to read which does not seem to be a problem in the PDF version.
4. From 'Get started now!' on the Meteor website '$ curl
https://install.meteor.com/ | sh' is the installation command which is different than '$ curl
https://install.meteor.com | /bin/sh' in '2.2.1 Installing Meteor' i.e. is there a difference to having ' | sh' vs. ' | /bin/sh'?
5. In '2.2.2 Setting up a new project' is based upon an earlier Meteor version example as noted by the newer version having a {{counter}} vs. {{greeting}} for the older version among other changes which could make it difficult for someone just getting started with Meteor to follow. Also, the code available from the publishers website is the completed code and not snapshots as the example unfolds which might not be as advantageous to learning. Along these lines, it might be helpful to work through any examples and commit them to GitHub at certain points in the process so it would be possible for a reader to be able to easily navigate the example to increase learning and understanding.
6. It would be great if the examples in 'Chapter 3 Working with Templates' were more user friendly in the sense of the reader being able to work through them in more of a complete example to be able to get more of a hands-on feeling of working through the code, i.e. the code feels like a snippet here and there where a reader could be missing the complete picture of what is going on and how the examples are all tied together.
These comments are all based upon reviewing the book on a variety of screen sizes and platforms from a 27" Late 2013 iMac to a 7" Late 2013 Kindle Fire including PC's running Windows 7-8.1 and a Chromebook with screen sizes from 11" to 18" where the PDF version seemed quite a bit more polished and easier to read than the Kindle version which seemed to have a variety of formatting issues which are sure to be cleaned up prior to production release.
Again, I really enjoyed the first three chapters and am really impressed with the material and presentation, but how could it be anything but awesome with Stephan Hochhaus and Manuel Schoebel as authors, but did want to give some initial comments on what looks likely to be an awesome Meteor.js book.