It is unusual to see that much space freed, but I just ran this d-u on my HP laptop, and it seems to be working just fine.
Calculating upgrade... Done
The following NEW packages will be installed:
libboost-date-time1.61.0 libboost-filesystem1.61.0 libboost-iostreams1.61.0
libboost-serialization1.61.0 libboost-system1.61.0 libboost-thread1.61.0 libicu57
The following packages have been kept back:
konq-plugins
The following packages will be upgraded:
apt apt-utils cpp-5 cpp-6 debian-goodies encfs fonts-opensymbol g++-5 g++-6 gcc-5
gcc-5-base gcc-6 gcc-6-base gir1.2-gtk-3.0 gir1.2-javascriptcoregtk-3.0 gir1.2-webkit-3.0
gtk-update-icon-cache konversation-data libapt-inst2.0 libapt-pkg5.0 libasan2 libasan3
libatomic1 libbluetooth3 libcc1-0 libcdr-0.1-1 libcilkrts5 libcmis-0.5-5v5
libe-book-0.1-1 libgcc-5-dev libgcc-6-dev libgcc1 libgfortran3 libgomp1 libgtk-3-0
libgtk-3-bin libgtk-3-common libharfbuzz-icu0 libharfbuzz0b libitm1
libjavascriptcoregtk-3.0-0 libjavascriptcoregtk-4.0-18 libkolabxml1v5 libksba8 libllvm3.8
liblsan0 liblua5.1-0 liblua5.2-0 libmpx0 libmpx2 libmspub-0.1-1 libpsl0 libpython2.7
libpython2.7-minimal libpython2.7-stdlib libpython3.5 libpython3.5-minimal
libpython3.5-stdlib libqt5concurrent5 libqt5core5a libqt5dbus5 libqt5gui5 libqt5network5
libqt5opengl5 libqt5printsupport5 libqt5sql5 libqt5sql5-sqlite libqt5test5 libqt5webkit5
libqt5widgets5 libqt5xml5 libquadmath0 libreoffice libreoffice-avmedia-backend-gstreamer
libreoffice-base libreoffice-base-core libreoffice-base-drivers libreoffice-calc
libreoffice-common libreoffice-core libreoffice-draw libreoffice-impress
libreoffice-java-common libreoffice-math libreoffice-report-builder-bin
libreoffice-style-galaxy libreoffice-writer libsigc++-2.0-0v5 libstdc++-5-dev
libstdc++-6-dev libstdc++6 libtidy5 libtsan0 libubsan0 libvisio-0.1-1
libwebkit2gtk-4.0-37 libwebkitgtk-3.0-0 libxerces-c3.1 libxml2 libxml2-utils manpages-de
most plasma-widget-amule python2.7 python2.7-minimal python3-uno python3.5
python3.5-minimal qml-module-qtwebkit qt5-qmake qtbase5-dev qtbase5-dev-tools uno-libs3
ure usb-modeswitch-data wpasupplicant
116 upgraded, 7 newly installed, 0 to remove and 1 not upgraded.
Need to get 303 MB of archives.
After this operation, 207 MB disk space will be freed.
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