My main issue with ORM's is it tends to treat the persistence of data as an after thought rather than being the really important thing.
The data is often much more significant that the app - in two ways - the value of the data outlives the life time of the app, and often the data has connections or uses beyond the app.
ORM's tend to result in an app centric, rather than data-centric view of data persistence.
Now you don't have to use it like that - but even if you design the schema and mappings yourself, you still have the problem of the ORM assuming it soley owns the access to the data - and if you turn off that assumption performance is often terrible.
If I had an app with modest performance requirements, where the data and the app where one - then that's probably the ORM sweet spot.
But if the data is important, has multiple uses ( and so you might want multiple views in terms of objects ), and will likely outlast the application then I'd stay well clear.
SQL is already a powerful abstraction - learn it instead.
The data is often much more significant that the app - in two ways - the value of the data outlives the life time of the app, and often the data has connections or uses beyond the app.
ORM's tend to result in an app centric, rather than data-centric view of data persistence.
Now you don't have to use it like that - but even if you design the schema and mappings yourself, you still have the problem of the ORM assuming it soley owns the access to the data - and if you turn off that assumption performance is often terrible.
If I had an app with modest performance requirements, where the data and the app where one - then that's probably the ORM sweet spot.
But if the data is important, has multiple uses ( and so you might want multiple views in terms of objects ), and will likely outlast the application then I'd stay well clear.
SQL is already a powerful abstraction - learn it instead.