Primary disadvantages at right for adopting .net core is its continuously growing ecosystem.
.Net core is still growing and it will take some time to become robust and diverse.
Continuous delivery of updates makes it harder to build and forget. Developer has to continuously keep up with the changes coming out of each releases. Some might be crucial like security updates and some might be as good as replacing obsolete methods with new ones.
So staying on a version that receives security updates is vital for any internet aware application. While the .NET core LTS promise of at least 3 years of support is mostly acceptable, it feels like a step back from .NET framework support, which generally received 5+ years. The current branch, with its promise of only 3 months of support, fails to meet even the minimum required timeline for me to recommend it for production code.
One of the great advantages of using a mature language and framework is the rich set of tools that are available to assist you in developing and monitoring applications.
Unfortunately, the tooling for .NET Core no longer reports the memory consumed or the CPU used by the process.
The good news is that things are getting better, even if there are occasional missteps. It will just take time for the ecosystem to grow as robust and diverse as it is currently with .NET Framework.
In an attempt to let developer chose which things to include and exclude, the packages have gotten a lot smaller. Is more granuarility always good?
In the Microsoft.AspNetCore.App metapackage there are 144 dependencies. How many developers will have time to look at the transitive dependencies of 144 nuget packages to see if they're all accounted for?
And there are 2 problems here -
First, it becomes very difficult to understand what you actually depend on. Very few people are going to actually use all 144 packages.
Lets say we trimmed down the package and remove unnncessary items.
Now in near future when we need to add something back, it is very difficult. Discovering that fragment is real challenge.