TL;DR: Right off I want to state that I think this pay-what-you-want product from Taskboy Games is worth picking up, even if you don't play Labyrinth Lord. I thought the information held within is pretty good, but the presentation could use some work.
I have to admit that I enjoyed reading this PDF. Some of this might be attributed to the novelty since I don't ever recall playing in or running a hexcrawl (straight-up overland wilderness...yes, hexcrawl...no). The main usefulness I see is the simple codifying of the procedures used to GM/referee a hexcrawl. I think most GMs would probably naturally take most of the actions listed in this reference, but I know myself well enough that there are some considerations I'd tend to gloss over without a set procedure. The author put forth some good ideas that might seem like no-brainers, but I highly doubt I'd have bothered to think of these unless I had done a bunch of hexcrawls in the past and even then....
While I liked the content, it really felt more like a magazine article instead of a self-standing product and I think overall this could have benefited greatly by some better formatting. The bottom of each page has a HUGE graphic and while some pages do have text coming down relatively close to the graphic, the realistic bottom margin on each page is just shy of 2.5". The side margins are just under an inch in width, as is the top margin (sans header). Altogether this whittles down the standard letter page 6" x 9" format. Between the truncated page size, overly large graphics, and basic font & paragraph layout it feels like less than a dozen pages of content have been stretched out to the 27 pages as presented.
How to Hexcrawl is a PWYW PDF with a suggested price of 99¢. While the usefulness for your campaign may vary, I found it a decent enough read.