Hi Tom,
That is mostly up to you. Ng2 is already in production by a couple of large google teams. However, it's still release candidate, and while unlikely and certainly unplanned, there might still might be a few surprise breaking changes coming along.
What goes for angular itself, can not be said for the tooling you need (just yet). This is still very much in flux, but once you have a project up and running, you are more or less freed from this. The angular-cli is a good place to start.
In Ng2 the service layer is 98% pure JavaScript/Typescript. Also, you don't need much from it in the WebAPI department. Some light wrapping of those into Observables is going to cover another large part of your app.
You can use/deploy observables completely decoupled from angular. (you can even use them quite well in an NG1 app!)
I have no idea when Ng2 is going to be graded 'production' ready, but give it a spin, or build a small prototype in it, and you can base your opinion on that. For a lot of use-cases, Ng2 is more then stable enough as it is. If you are going into a long-term project, you should give it certainly a fair change.
Hope this helps you a bit,
with kind regards
Sander