Currently SharePoint 2010 is in Beta 2 phase and I am investigation the new possibilities given by the new External List feature.
During the investigation found few limitation that I will document them here:
- RSS feeds are not enabled
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Creating Access View not working
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Data Sheet View is disabled
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Export To Excel is disabled
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Adding extra columns not from the external content Type are not allowed
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Ratings and Workflow are not allowed.
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Trying to change “Information management policy settings” gives error.
SharePoint is currently only in the beta phase but It seems again that external list have a lot of limitations and I don’t know how much of them will be removed by RTM.
Even if Microsoft was trying to make the External Lists to be as transparent as possible for the End User we’ll need to be careful when recommending and use this list because of the existing limitations.
I have hoped that when Microsoft have designed this External List to just decoupled the data storage and data access layer from the rest of the SPList type.

[...] External Lists Limitations in SP2010 [...]
Also there are no event receivers on the lists, so you cant hook into changes or use workflow. Now thats a bummer…
[...] This post was mentioned on Twitter by Jeremy Thake, Jeroen Derde. Jeroen Derde said: RT @jthake #sp2010 extrenal list limitations: http://bit.ly/5ol6NW [...]
I think `external lists` are the new version of an old concept (BDC) and comparing to MOSS it`s way more advanced now. Comparing to other lists, external list is not so advanced
and I don`t think it will be by RTM. Great post btw.
In addition to the items mentioned, based on personal observations, I believe that External Lists are not exposed through the RESTful interface that comes with SP2010. Have not read about it anywhere, so looking for someone to confirm this.
They were talking about this at SharePoint Saturday in Chicago. Basically with BCS you are hooking up to data from a completely segregated environment (SAP,Oracle, etc) without any knowledge of how often the data is changing. From what I remember they said that the development team was not comfortable with that. And why they didn’t support firing workflows or event handlers from it.
Hello.
You can use my free plugin for this. http://exportexternallist.codeplex.com/
It will install new ribbon button to any external list and it will generate the excel document.
enti