What are downsides and upsides of Entity Framework in .NET?

We've been doing a series of posts on the Safari blog about Entity Framework. You might find them helpful - http://blog.safaribooksonline.com/2013/05/20/entity-framework-using-database-migration-to-seed-our-database/

Believe perf issues are well handled come EF6. However, accommodating changes to the model is still problematic. Even seeding is tricky and attempts to address these issues are many and not wholly successful. Handling model changes is a biggy though as EF is all about letting you build out a solution from POCO and those classes are invariably subject to revision. Data Migrations is still not robust enough imho and breaks too easy. It's a huge improvement over, well, the absence of migration handling but while in theory it is transparent, it just doesn't work well enough in practice.

MindScape has a product that compete with EF, Take a look at http://www.mindscapehq.com/products/lightspeed and they have done some comparing against EF.

Speed will be a factor. Although EF has made drastic improvements in this area, I still prefer https://github.com/SamSaffron/dapper-dot-net for a .NET ORM

Advantages: Fast and straight forward using LINQ/FE objects For Add/Modify/Delete/Update, Easy to map business objects (with drag & drop tables on environment). It keeps a good performance when you work with a small / middle domain model and Less coding required to accomplish complex tasks. DisAdvantages: If there is any schema change in database FE will not work, we have to update the schema in solution as well! and as the queries are dynamic there might be a hit in the performance of the application.

Entity Framework and any similar technology has one fundamental philosophical flaw: it assumes that an application developer has complete control over the database.   In an enterprise world this is simply not true and unlike using SQL language, Entity Framework is not flexible enough and is simply unable to accommodate all possible database designs.   In most enterprise settings database is completely outside your influence and you are designing or maintaining one of 50 or 100 different applications using it. Even if the tables you are currently using will work with Entity Framework, there is zero guarantee that: 1. the DB design will not change for reasons outside your control to a state where Entity Framework cannot work with it, 2. Microsoft will not abandon supporting EF and instead will run after something more shiny 3 years into your lifecycle (something Microsoft does quite often). SQL is "eternal" because it is a natural scientific outcome of a concept of a relational database. You can use the same SQL for as long as relational databases will exist, by comparison Microsoft introduced and abandoned several mapping technologies in just the last 15 years. Now, if you are writing a relatively simple application that can be completed in 6 months and will have a lifecycle of 5 years , you are good to go. But look at my situation for example: I created a massive industrial web application. Its primary development took 10 years. It will be in production quite possible for 25 years. Can you imagine me chasing after every new concept Microsoft introduces when my development started under MS Windows XP, IE 5.5 and .NET 1.1??? On a system spanning 14 separate programs, with a million LOC there would be no time for primary development, all we would do is constantly update code to the newest shiniest MS data mapping tech. On the other hand queries written 2004 still work in 2016... People in the corporate HQ can still remove my indexes and primary keys from the central DB without telling me and the application still works...   To sum up: Form a technological point ET is great, assuming you have full control over DB design and maintenance and you are not the guy who will have to explain 7 years from now why the company has to spend $150k, because you used a technology without staying power.