People complain all the time, while I am like...
SUCK MY COCK, SCYTHIA STRONK (stand-ins for Poland, but holy shit that healing after killing enemy bonus is amazingly powerful)!
I must say that this game is... not as good as previous ones after all the expansions and updates (there is distinct lack of Winged Hussars) but it is much more complete than previous one at start and while some graphical things (Leaders, Dear Emperor, at least some of them (Scythian queen is 2manly4u, as it should be) like the Mvemba(?) or Cleopatra) are really bad, I actually like the units. They apparently finally have some sense of scale, Catapults are bigger than people.
The game indeed seems pretty easy but eh, I myself enjoy the empire-building aspect and don't need to be constantly murderized from every direction, albeit it would indeed be fun if the enemy fielded similar-tech units against me.
The AI actually gave me pretty decent deals - I got a lot of Luxuries and I traded them all the time for money, so I was literally swiming in money. Only when the enemy stopped to like me they started to make ridiculous requests. Be careful though, negotiations with them are useless - each time you try to get more favourable one they will change it to even worse.
As for backstabbing - I think it heavily depends on the leader. Gilgamesh hugged me with his manly arms from the start and even later on when the relations inventably detoriated to unfriendly he did not attack me and generally we both enjoyed the trade and ganked everyone else. Trajan was also a pretty nice guy, the best deals I got were from him.
Pedro and Catherine were dicks, though.