Interop with other systems can be a tricky business - WCF is the only platform around that supports a plethora of WS-* standards - most other platforms only support a few of those, so the wsHttpBinding protocol can be "too much" for the other systems at times.
BasicHttpBinding is okay - but it's old, legacy, only for backward compatibility, doesn't offer much in terms of security etc. I would recommend: try to use wsHttpBinding whenever possible, and only fall back to basicHttp if you really must. But always try wsHttp first. It offers just so much more in terms of security and flexibility.
The DataContract is an entirely different matter though - it's really a .NET wrapper over XML schema (XSD files), and this is one of the industry standards that has very broad and very complete support across the board. So the [DataContract] part of WCF doesn't feel like a problem area.
Yours problems will most likely appear in areas such as support for various SOAP versions, different expectations about text encoding, and - of course - security settings. But I can assure you - with WCF, you are in a uniquely great position since WCF can be tweaked to support even the craziest and most exotic web services and web service clients out there!
It might be a bit of work and require a bit of tweaking - but WCF does give you the necessary tools and extension points to do this successfully.
Marc