I've never known any release of SQL Server to be categorically "unstable". Every release fixes some issues and introduces new issues, but every experience is unique depending on what features you use and how you use the product.
I've worked for companies in the past who would sit on a specific release of SQL Server for several years and dismiss new releases with skepticism. Maybe executive management doesn't trust Microsoft to release good products, or maybe it's not trusting their IT staff to handle the upgrade process and code changes. But without trust the IT organization becomes stagnant, and even the good staff members will start to leave.
The main considerations are:
- Will this new release have integration issues with my existing 3rd party tools and applications, and are there upgrades for these products as well?
- How will this new release affect my SQL execution plans, and can we readily mitigate this?
- What are the costs for the upgrade?
"Do not seek to follow in the footsteps of the wise. Instead, seek what they sought." - Matsuo Basho