I've got to say, alliances in RTW are, though flawed, a nearly infinite improvement over MTW. I've had alliances last well over 100 turns, even in the unpatched 1.0 version.

That said I've never been really assisted by an ally after requesting assistance, and the alliances do break down fairly often for completely unknown reasons (and I suspect rather random reasons), but it is an improvement. Let's hope that M2TW takes the apparent randomness out of it with the worsening/bettering notifications, etc.