The long-rumored "Facebook phone" is set to finally come out on Friday. In addition to the HTC First, which will have Facebook Home built in as the native operating system, anyone with an HTC One X, HTC One X+, Samsung Galaxy S III or Samsung Galaxy Note II can download Facebook Home for free from the Play Store starting tomorrow.

The question is: Does anyone want Facebook to take over their entire mobile device? There are concerns over privacy, battery life and functionality; even Facebook's traditional set of mobile applications don’t have the greatest track records. Can Facebook handle an entire operating system?

Believe it or not, the majority of early reviews have been mostly positive. On AllThingsD, Walt Mossberg wrote that Home is elegant, easy to use and addictive. He added that even as a regular Facebook user, he found himself paying more attention to his News Feed with Facebook Home. Mossberg didn’t notice any significant change in battery life while running Home.

TechCrunch’s MG Siegler agreed with the word “elegant,” adding that Facebook “really nailed the interaction element on the home screen.” Siegler said he liked Facebook Home’s notification system better than the native apps on both Android and iOS, but wished it could access third-party notifications.

A CNET review applauded Facebook's new Cover Feed for its design, functionality and aesthetic beauty, but added that the phone feels divided between Google and Facebook. Engadget’s Brad Molen also raised some concerns about Cover Feed, writing that a program that continually updates Facebook in the background could potentially have a huge impact on data usage. He noted that users can adjust image quality to low, medium and high to conserve data, but a WiFi-only option is unavailable. His testing found that just running Facebook Home on the medium setting would eat up one-quarter of a 2GB data plan.

Perhaps the most universally praised element in Facebook Home is the “Chat Heads” feature, though the name is roundly despised. The Verge called it “a stupid name for a great idea” that forever changes the way we chat on a smartphone. Siegler also praised Chat Heads, saying that it is “absolutely how messaging should be done on a smartphone.”

The New York Times' David Pogue had some negative things to say about the app-launching function in Facebook Home. While he agreed that Chat Heads is fun and engaging, sending a new message isn’t very intuitive.

Mostly, Facebook Home is designed with Facebook enthusiasts in mind, but probably won’t be able to convert the skeptics. As for the HTC First, several reviewers have praised the phone for being a perfectly functional yet totally unremarkable phone that would be a great purchase for Facebook fans looking for an inexpensive smartphone.

Will you be downloading Facebook Home on Friday? Which functions are you most looking forward to? Let us know in the comments section below.