The only pain point you can have is if you refuse to use Google Play for installing apps. Well, Android allows you to install apps from third-party app stores or websites (e.g. Amazon's App Store), but most devs are on Google Play.
I'm a heavy Google services user, however I'm using lately K-9 Mail instead of the GMail client, because K-9 does encryption. I'm also using OsmAnd+ in addition to Google's Maps. I don't even have Google+ installed (though I do have a Google+ enabled account).
I've read reviews saying that SMS has been integrated into Hangouts.
And if you don't like the Hangouts app for some reason, you can easily replace it with one of the many SMS apps out there.
The only place I could think of where the integration is jarring is the photo uploading feature, but I've simply told Dropbox to do it instead.
And that isn't worrying to you? People can add you to their G+ circles and there's no way to stay hidden. So Google gets to collect all the information about people you associate with in order to sell your personal info better (to the NSA, among others)
I'm under no illusions that there is much I can do to stop Google tracking me, occasionally pushing stuff at me addverts and so forth), and trying to "lock me in" where possible, as I use my stock Android devices. I'm sure both MS and Apple either d the same sort of thing or will as soon as opportunity presents itself.
I'm not saying it is right of course, just that if it is a particular problem for you then it should inform your decisions before buying a device. Also I suspect buying and returning devices as a form of protest is not seen the same on relevant internal reports, and is likely to inconvenience your retailer more than the manufacturer, so if you wish to protest the behaviour you will find simply not buying to be more effective.