Quality of product - GA Premium is just as easy to use as the regular version, but more powerful in terms of the amount of data processed. New reports, enhanced features and data collection power are introduced all the time, always thoroughly tested for user experience and stability. The Analytics Help Center, developer guides, and other training resources have really improved to cover different levels of implementation and usage. I find that the product enhancements chosen to release over the years reflect that the GA team really takes the time to listen and evaluate customer feedback. Yes, some features are long overdue but many times it's because they need to make the features flexible enough for wide range of use cases.
Customer service - GA Premium is the least sales-y vendor I have ever come across. Every conversation I've ever had with the team after becoming a customer is always about what our pain points are and how they can help solve. Even their annual summit is all about the product, not to up-sell us on other products or services. The technical support turnaround time has improved throughout the year. They even answer Google Tag Manager questions! I also appreciate that they actually test the solutions before recommending to clients, never just canned responses.
Stability of the platform - I've set up 50+ sites in GA and scheduled hundreds reports, dashboards, alerts, etc. by now and never have to worry about stakeholders not being able to access their GA accounts or not receiving data as scheduled. I'm grateful that GA sits in such a robust infrastructure. The GA Premium contract also extends SLA to Google Tag Manager, which brings additional peace of mind.
Value - If none of the above is attractive enough, the $150K flat fee a year for a large enterprise should be enough to qualify GA Premium for serious consideration. This includes Premium-only reports, unsampled data, 24/7 technical support, BigQuery data storage and query, etc. It is great value.
The native dashboard tool could use some updates so more GA reports/tables can be added to dashboard or more visualization can be available. It'd also be great if the shared dashboard could be more interactive, especially for clients without licenses to data visualization software. The GA add-on helps mitigate this problem but I imagine select user segments would prefer to stay in GA interface to build out meaningful dashboards.
Personalization and/or experimentation features are currently lacking in GA. To be fair, none of the other major digital analytics solutions have figured it out yet either, but eventually it'd be a time saver to be able to at least run experiments within a digital analytics tool.
To understand the performance of acquisition campaigns and websites/mobile apps as well as the ROI of leads/transactions generated online. Also to understand the above on the enterprise level, across multiple sites. -> The benefit is to be able to analyze such data and optimize accordingly.