Not really, or at least not offensively so. There should be an option that pops up on installing the mod to choose between a core experience and an 'expanded' experience. Not sure if those are the exact terms as it's been awhile since I myself last used it, but nothing extreme is changed on choosing the basic option and it's worth installing for the fixes it provides.krellen said:Warning: that mod actually changes the gameplay from the developers' intent.The Madman said:Just the unofficial patch which is available here really.
Obviously if someone wanted an absolutely 'pure' playthrough just using the developer patches and playing entirely without mods is an option, but aside from fixing a few game-stopping issues the official patches don't do much and the game is still a fairly buggy and flawed experience as a result. Myself, I'd say installing that fan-patch I mention above is worth it. There might be some slight changes even with their basic option, but even so it just allows for a smoother and more enjoyable experience.
That's my take anyway.