Installation broke a multilingual site - so better use it on a single language site only!
Some articles do not show up at the (html) sitemap (Probably because there's no menu pointing to them, although they are accessible through the tags).
The links in the html sitemap must be ordered by hand(!), which renders the sitemap feature useless for huge sites, well you can leave the links unsorted which looks very unprofessional.
Data entered at MijoSEF Metadata is ignored/gets overwritten as soon as an article is saved!
The MijoSEF Metadata is displayed at every tab at the Edit Article page - displaying it only once would be enough.
MijoSEF brings it's own TAGS system which is useful for joomla 3.0 and earlier, but obsolete for joomla 3.1
On the other side, there's a +1 for the highly responsive and competent support.
To conclude it: The flaws render MijoSEF utterly useless for my requirements. Given the high amount of excellent reviews, I'm quite disappointed.
The only downside is, if a network is blocked by a firewall, enabling it leads to a white rectangle, which is noticeable on templates with none white backgrounds only. But clearly worth 5 stars anyway!
Thank you very much for your review!