Gotchas with Php and Postgresql?

I'm preparing for a large project in which I'm the sole designer/developer. I've just about made the decision to go with Postgresql, as part of the project is converting a MS Sql Server db to a open source db and I think Postgresql provides some features that will make this port easier. However, just wondering if there're any "gotchas" I need to consider here. I'm definitely using PHP to write the app, and I can attest to PHP's great support for mysql (used it many, many times), but I have no experience using it with Postgresql. While I suspect that it's just as easy to work with via PHP as is MySql, I'm looking for any hardened, trenches-earned wisdom anyone would like to bestow. Thanks very much. John