First of all, this is a very complex and powerful software. I was using shotwell to manage my photos over quite a long period, but it's capabilities are limited. Wherever you go, digiKam is recommended instead.
And well, this is true. The best things in digiKam so far are hierarchical tags and automatic face detection. But on the other hand: why is it not possible to simply export the images and remove metadata or resize during that process? You even have to use the 'external Storage exporter'-Plugin, which of course is not included in digiKam, but lives in the kipi-Plugins.
But the worst thing of all: Every once in a while digiKam just crashes. Maybe it is so dependend on some KDE things, that running it under XFCE is just unstable. Usually this is not such a big problem, simply restart it again and everything is back. But today, it had decided that it was going to reindex all files again.