In my first game, a Julii campaign just for the sake of messing about. The Gauls were my main diplomatic contacts; I asked them for a ceasefire because although I was beating them in the field I desperately needed to sort my negative cashflow and reinforce my troops. The Gauls agreed, they even paid tribute of 2600. On a whim I asked for an alliance; it was accepted. Next turn they broke the alliance. I repeated this process, with around the same amounts of cash each time, every turn for something like 6 turns. My finances were so bad even the huge tributes left me with a negative each turn.

Now I am doing a Brutii short campaign with more serious intentions. This time everything is going quite well, but diplomacy remains ... odd. I allied with the Macedonians; it lasted for maybe 3 turns before they marched an army in and started attacking my cities. I then forged a peace and alliance with the beleagured Greeks to take on Macedon. It lasted one turn.

My Roman allies have been very good, declaring war and ceasefires to match my own dealings, also sending armies to protect my cities from rampaging rebels.

froggy conclusion: non-Roman alliances aren't worth the paper they are written on. The Roman alliances are great, everything I had hoped for.