1) Dead simple in it's usage
2) Can configure / tweak almost any parameter
1) At least on Linux, it doesn't & can't use pre-installed versions of 7z, upx etc etc from system folders.
Someone has to explicitly replace the versions under the /res folders.
Which is obviously simple enough...that's not the point though.
Thing is, it would be nice if it could automatically recognize that said executables might already be in the $PATH, and use those instead.
Also, at least Debian / Ubuntu & Fedora are not really 'happy' (for a lack of a better term),
including software in the repos that comes with ready-made executables from elsewhere.
Ie. if Peazip could recognize 'system versions' of 7z/upx etc, possible inclusion in such repos would be far easier...
2) Not really a con...just some thoughts: QT4 has essentially been removed from the by far vast majority of distros...
so not sure if it's worth maintaining such nowadays (ie. if there aren't any plans of moving on to QT5).
GTK2 has also started fading away...although it will still be around for a few yrs (and hopefully Giorgio won't abandon the Linux version when such gets removed from distros as well).