Wow.  That was insanely hard.  It took me a solid 2 days to complete (4-6 hours?! no.).  Here are some tips:

• It has been updated in the past few weeks, so beware of older comments and screenshots that people share.  You should NOT copy them!
• Detail, detail, detail.  For ALL items you create, copy and paste the names into the blanks - report names, dashboard titles, group names, etc. Check twice.
• Expect to run into "bugs".  There were easily a dozen that I had to work around carefully.  It started with importing data needing to be CSV parsed, and ended with not being able to move the Lightning report into a folder.  
• Before hitting the "Check Challenge" button, re-read the description of the step!  And always do them in order.  They build on each other and are pretty good about telling you what will be checked. (in this SuperBadge, at least..)

Now, some specifics about the steps:

1. Data import was a bit off.  Excel doesn't like to export 1 tab at a time, so be very diligent about checking each CSV to see that it's good.  For some reason, the Hobby list gave me problems, so I added some data that I never mapped upon import.  And details.. a lot of details.
2. There was an underlying report that wasn't really discussed much, so I had to create it carefully and tweak it until it did what I wanted.  And again, details.
3. Flipping from Classic to Lightning is easy, but you have to be sure that everything is there and ready to go before you do.  As I found out the hard way, you can't edit in Classic after you start editing in Lightning, so that affects this step and step 6.  Oh, and details.. names, etc.
4. I can't remember anything specific about this step.  But, details.
5. I did these reports first (before checking any challenges), and it took a LONG time.  There are so many parts to get right.  The custom report type is the real key, though.  Read very carefully when setting it up, because a wrong choice there will cascade down to all of the reports and make life miserable.  Also, for some reason, my matrix report kept re-inserting columns that I had removed, so I had to check that report EVERY time I edited it.  Oh, and details, once again.
6. This one was pretty easy once I saw the notes at the BOTTOM of the description (about creating the user, etc.).  I had already worked on the Security Superbadge (stuck, tho) so I knew how to work these well.  But as I said earlier, the Lightning Dashboard gave me the worst trouble.  I found a SFDC webpage that said it was impossible to move the dashboard into another folder!  So, improvise, which ended up working.  Oh, and yea, as you would guess... details!

I LOVED this challenge.  It took me probably 14-16 hours.  But now I feel very versed in these topics.  Thanks, SFDC and TrailHead folks!

The first challangeof this Superbadge seems to be problematic, showing the following message:
Challenge Not yet complete... here's what's wrong:
We could not find enough records in the 'Contacts' object. There should be at least 100 from the import.
What is interesting is that everything seems complete to me! I have inserted 100 contacts and 100 accounts, and of course all other items (Opportunities and Contact Hobbies).

Any idea why I see this error message?