I've been running Yosemite on my Mac Mini for a while now after upgrading from Mavericks. All my old applications work fine, and I've experienced no problems. iWork works fine.
However, as you say the Photo app is weird, having rearranged my pics from my large iPhoto app and doesn't have some of the great features of iPhoto. I do use the Photo app. But I kept the old iPhoto app, and when you open it there is a reminder that changes won't be reflected in the new Photo app; but both can co-exist. Just be sure you have backups on an external drive that is kept safe.
I might try to reinstall Work.
Did you have an option to keep iPhoto instead of installing Photo.?