I ordered a DJI mavic 2 pro just recently.  And I've been reading so many negative reviews for the DJI Go 4 app for Android.  I am thinking about cancelling my order.  Should I be concerned about any serious problems with the DJI Go 4 app and the Samsung Galaxy s8 with Android version 8.0.0?

Short answer is no. If you set the parameters right in Android it works fine.
Follow this link to do it right.
Install-dji-go-on-an-android-tablet-or-phone

There have been some reports on DJI Go 4 app for android as well as for IOS. Some claims they have problems with the app on some phones but some also claims it's running smooth for them.

Hi MeteoricDragon. Thank you for the inquiry. I understand that you are inquiring if the Android devices like the Samsung S8 will work well with the DJI Mavic 2 Pro. We highly recommend you to use the recommended mobile device for the DJI Mavic 2 Pro for compatibility and reliability purposes. For reference I will post the list of recommended mobile device for the DJI Mavic 2 Pro. Thank you for your support.

I have the Samsung Galaxy S7 and the DJI GO 4 app works great for Android.

I use a Samsung Galaxy S5 for my Mavic Pro and it works fine.
So no worries. Order it, enjoy it and don't give a f*** on the reviews in the appstore.
The most of the people are hater

I use the Samsung S9+ with Go 4 and it works flawlessly!

i have S8 plus and work great with Go4 app. And I always have AZ Screen Recording running while flying without any issues.

I'm wondering why the Galaxy S8 is not mentioned in the official compatibility list. There is S9+, S9, S7, S7 Edge and so on but no S8.
Only S8+ is mentioned.
Is there a problem with the S8 or was it just forgotten in the list?