Photos will not allow me to set the key picture for the album or event

That are all good points - but Photos is a completely new application. and it is only version 1.

Continue to use iPhoto, girraween; the next update to Photos will probably add a few more features.

iPhoto 9.6.1 is working very well with MacOS X 10.10.3.

The migration let iPhoto installed and also your iPhoto Library will still work with iPhoto.

If you did not uninstall iPhoto, it will still be there in your Applications folder. And if you had updated to the latest version iPhoto 9.6.1 before you upgraded to MacOS X 10.10.3, you can simply drag iPhoto back to the Dock from your Applications folder and continue to use it. Double click iPhoto and confirm, that you want to open iPhoto and not Photos. It is not compulsory to use Photos, while it it still the first release. When you launch iPhoto, you will see a warning, that the iPhoto Library has been migrated to Photos, but simply click the "Open iPhoto" button.The library will still work with iPhoto. ()see: If Photos won't open a library that you already migrated - Apple Support

If your iPhoto version is not iPhoto 9.6.1, you need to update it.

See this User Tip:

Usually it will work to reinstall instead of updating:

Get iPhoto 9.6.1 if you didn't update before OS... | Apple Support Communities

The main idea is to move the iPhoto app to the Trash, so Spotlight does not see it as installed, reload the AppStore, and then to try to download again from the App Store - from your Purchases tab, not from the main page, since you can neither buy iPhoto nor update it, but you can reinstall, if your AppleID is associated with it.

Meanwhile you may want to send a feature request to Apple using the feedback form. Apple - Photos - Feedback

I hope, Apple will listen and add more features to Photos to make it usable for large Photo Libraries.

Photos now take up 700Gb whereas it was 350Gb #@!$#@!@#!@#

That should not have happened. Photos will create a new library, that looks like having the size of the original iPhoto Library or Aperture library, but both librarys are sharing the photos: See: Photos saves disk space by sharing images with your iPhoto or Aperture libraries - Apple Support

Also, have a look at this document: How Photos handles content and metadata from iPhoto and Aperture - Apple Support

new PHOTO app replacing iPhoto bugs/ Problems OTHER PROBLEMS :

- no longer has a five star rating system

- my keywords for selecting albums are gone.

- cannot copy location of one photo to another

- cannot have an album with keywords AND rating > a value

- cannot set key photo of album/event

- multi parameter search feature gone

Anyone got any ideas how to get around this terrible downgrade of the software ?

All your keywords should be there- there must have been an error with the migration, if keywords are missing.

The five-star rating have been migrated as keywords. If you assign keyboard shortcuts in the keyword manager, you can assign the ratings by quick keys.

Locations cannot be added at all -there is no work-around other than adding locations in iPhoto or aperture before importing the photos to Photos.

Batch changing is also no longer possible. I wrote a few scripts and posted them in the User Tip section.

girraween81 wrote:

Photos will not allow me to set the key picture for the album or event - it is set to grey !

Have you tried opening an album (so its photos are shown in the main window) & then right-clicking on the one you want to be the key? When I do that, the second item in the contextual menu that pops up is "Make Key Photo" & that is exactly what it does.

Does this not work for you?

Apologies(!) - it works for ALBUMS but not SMART ALBUMS - it just chooses the last pic in the list.

For smart album the key photos are selected automatically. There is nothing you can do. "Make key photo" is not available for smart albums.

You could however import an additional photo to photos, that you want to be the key photo, and then simply adjust the date of this key photo by 1000 years or so. If the photo is newer than all photos in the smart album, it will show as the key photo.

The first screenshot should have been this: