Liferea is my Unix feed reader of choice; it definitely runs on Linux and probably runs on anything with a recent enough set of GTK / GNOME libraries. However, I've found that I need to add some patches:
|Fixes the bug where liferea truncates Atom 1.0 HTML entry titles that have HTML markup in them.
|Makes liferea prefer the <published> time over the <updated> time for Atom 1.0 entries if both exist for an entry. Without this patch, liferea decides that the entry's time is whichever one was the last it saw. This patch also changes the English text for an element to be more applicable for both feeds and entries.
These patches are both against liferea 1.0.9, the current version as I
write this, but they should apply with relatively little problems to
prior 1.0.x versions. They should be applied in order, with
(At some point when I feel like fighting with SourceForge's bug tracker I will try to report both of these as bugs. Feel free to beat me to it.)