Well this is fun. The course material is good but expects you to also have a good attitude. There are some hints, but not these are not enough to root machines alone.
This is not a bad idea. I have looked at lot of different courses for Penetration testing and found that Offensive Security to be at the top of most wanted. I also found that most offensive security users do recommend the labs here at Virtual Hacking Labs.
I purchased the 1 month course, as I have already completed the course work for Offensive Security Certified Professional but do not feel confident enough to take the exam just yet.
The labs are great and challenging. At the time of writing this (22/12/2019) I have completed all the basic servers and about 5 or 6 of the advanced server. I have only been at it for about a week and need to root at least 20 for the certificate of completion.
They do provide hints for the easy and advanced servers but of course less of a hint for the advanced. These are great servers for my weak spot of privilege escalation.
Update 10/01/2020: I have now completed this course and submitted the request for my certificate. This requires me to submit proof that 20 servers were rooted. The proof needed to be in the form of a word document. Screenshots, keys and notes were required for each server.
Update 13/01/2020: Certificate received: