GNOME 3.10 has some parts in experimental .
For e.g. :-
$ apt-show-versions -a empathy
empathy:amd64 3.8.4-3 install ok installed
empathy:amd64 3.8.4-3 testing debian.ec.as6453.net
empathy:amd64 3.8.4-3 unstable debian.ec.as6453.net
empathy:amd64 3.10.1-2 experimental debian.ec.as6453.net
empathy:amd64/testing 3.8.4-3 uptodate
As can be seen empathy has 3.10 in experimental. I have added all the sources as I have and want a mixed system.
But the whole gnome 3.10 is not yet in experimental.
For a status of which packages are in testing, which ones are in unstable/sid and which ones are in experimental.
Now, there are things to understand and think about. The ones in experimental may or may not work. I wouldn't recommend running GNOME 3.10 unless you can live with a broken system.
If you think you can handle a broken Debian system, sure. Do you know for instance what to do if libpam0g breaks, preventing all logins or do you know what to do if grep breaks, causing the boot process to hang forever? These things have happened. They will happen again.
If you want to still go ahead, go ahead, the only advice I would give then is to not to either use in a production system or make debian install on another partition and use/test it there.
the rest is upto you.