NetSuite Support
Overall NetSuite support is better than most enterprise support.
They provide a knowledge base called SuiteAnswers. It has many great articles. The only missing category of content that I noticed was the lack of SuiteScript 2.0 documentation and what was there was very basic and incomplete along with straight up errors. This might have been fixed by now, but a year ago it was extremely lacking. Another smaller issue is that you need to connect to SuiteAnswers from NetSuite before you can access the content. Not a problem when looking for information from NetSuite. However, this prevents sharing links with others, until you figure out that they need to go to SuiteAnswers themselves via Support > SuiteAnswers before they use the link you provided.
Support tickets are easily created, and they will keep you updated via automated emails along with reaching out to you by phone so be sure you configure and check which phone number is prepopulated on the form before you submit it. Their categorization of issues is pretty good though they could step back from their company organization and look it the categories from an end user perspective. On many occasions the common issues that one experiences with a SaaS solution do not map directly to their categories. To minimize the chance of you losing your description of the issue I would suggest you type up your description before initiating the ticket creation. On several occasions I have worked on the description online only to lose it with changing some of the above fields or session timeouts.
As for phone support, I believe that there is an additional charge to have it included. Ours is 24/7 and most of the time we can directly get to the first level support with minimal hold times. The main issue that has happened a couple of times for me is for the rare complete outage or for when the authentication service goes down, you cannot log in and create a ticket. During these times phone hold times go thru the roof. It appears to me like they use a different NetSuite account to manage the support cases. Using your own service to manage support cases might be reasonable for small to medium sized companies, but not appropriate for large international companies. They managed the access to the phone support by having named accounts and allow you to set these via the NetSuite Support Center interface.
Keep you NetSuite account number, their telephone support number along with your account manager's phone number handy and not in NetSuite so you will have access to it when you need it the most.