I'm not a fan of AOP. I think that in a well design (layered) system there shouldn't be any "cross cutting concerns". Each layer should deal with his responsibility/es. Security is always given as a example of "cross cutting concern".  But i disagree with this.....security is a top level "concern". There's no point in checking credentials/access rights  AT every level of the application.  Not to mention that usually the security features of a application usually permeate to the UI level (as an example.....if the user has the option to edit a record...if it doesn't have the rights to edit it you simply disable the button. If don't let him type and then go 2 layers below to check for rights and then you show a error message....that's bad UI).

Security should really be enforced in the "entry point" layer of the system (be it UI or service).

Well,  i have been working with EF for a while and here are a few impressions :

the good :

- has UI (designer) tool for (automatic) mapping.

- offers support for advanced mapping (unfortunately in the first version only if you edit manually the xml mapping file).

- full LINQ integration (by far the biggest advantage).

the bad :

- on the persistence front,  it has support only for the "big brother" (in this case ObjectContext) which manages entity state and persist them. It doesn't offer a API to do "manual" operations. This makes it very awkward to use in ASP.NET (where most likely you'll have a ObjectContext per request and the entity state can't be tracked down automatically). From my point of view this is by far the biggest disadvantage of the API.

- support only for SqlServer.....i think it will be a while until we can use with something else.

- the MetadataWorkspace used for querying mapping data is a bit hard to use (this is especially bad considering that the first version of EF doesn't support POCO persistence).

the ugly:

- the VS  designer. I hate that crap. It gets unusable with many entitites and it generates all the code in a single file (nightmare for source control).

Plus it's  integrated in VS ( and in this case this IS a BAD thing).