I'll start this by saying I was skeptical, I only play Warcraft with a routine. I do not play the game seriously or take raiding seriously so simcraft wise I cannot comment though I do raid. I returned to Legion to do the content that will disappear when BFA comes out.
Please note that I used the Warrior routine which is community based i.e. not an official profile from the guys + the Paladin routine which is the official version (49eur).
Install - 10/10
The install and configuration of GG is easy, pay good attention to the instructions as even the smallest detail will make a difference.
Performance - 8/10 (Warrior + Paladin)
This is NOT something that you press a key and take your hands away from the computer, you will have to be present, I've seen a few comments on other platforms where it wouldn't cover absolutely everything and largely you can with hotkeys/macros etc. I am under geared as I just returned and everyone seems to be 900-910+ whereas I sit at around 880/885 but I was pulling very good numbers on the warrior/paladin respectively. So why not 10/10!? Because the holy paladin doesn't perform great and lags, causing me to be kicked from the group however I will also add that there is a healing engine being developed which will replace the way it heals at the moment. I would also like to mention that during the setup you are also given the macros required for the abilities, very very useful.
Support - 10/10
This is probably the best part of the whole GG experience for me thus far, even though it is only a few days the amount of support I have received from a staff member has been brilliant. Questions, setup, opinions on BFA, classes etc. has been answered and in detail I may add. I cannot say anything negative about the support at all, absolutely brilliant.
Cost
I'd say the 49 eu + renew cost is fair considering most specs are covered, the community made profiles are more than adequate, there is a chap that makes an incredible effort on there from what I have seen. Considering you have to pay an additional fee for the BFA profiles I'm not sure anyone can argue against it, at the end of the day it is development time to do these profiles and you get what you pay for, considering it is greatly discounted again I cannot argue.
Looking forward to BFA and I'd like to see the casting profiles, if I do end up purchasing one then I'll review here again.