As probably one of the most widely known anime series to westerners, it's likely that every anime fan will have some kind of opinion on Naruto, whether they've ever seen it or not. My current musing on this phenomenon of a franchise is whether the series is overrated and not at all worth the hype or if in fact, it's undersold and it's true brilliance hidden. I have come to the conclusion that in truth it's actually a mix of the two.
What draws me to this way of thinking is the series' overwhelming popularity and the phenomenon known as the "Narutard". While popularity is generally considered a good thing (particularly in western countries that naturally don't get the wide variety of shows/merchandise) when a certain fandom gets repeatedly shoved in your face like a clown who just discovered the custard pie and doesn't know when to quit, it does more harm than good. Undoubtedly this is the case with Naruto, whose gleaming success and rabid fanbase have had two significantly negative, yet utterly contrasting effects.
First off the hype surrounding Naruto has a habit of massively overselling it. With so many people raving that it's the most awesome series ever to grace our screens, it's unlikely that any show, let alone this one, will ever manage to live up to the expectations planted in your minds. I personally love the series, and have done ever since four years ago when I marathoned through series one and the first thirty odd episodes of Shippuuden. However, even I have to admit that the anime is overrated in comparison to the impression many of the hardcore fans will give you. That being said, the manga with it's tighter pacing and concentrated plotline unhindered by filler does live up to the hype, though still not up to the Narutard levels of being the greatest story ever told.
On the other side of things, the show's popularity serves to massively undersell the story's worth. With the fandom being hurled at you every which way it can likely have the effect of making one boycott it on pure principal. When confronted with legions of people in Konoha cosplay or Akatsuki cloaks at any anime-related event and Narutards running around adding "no jutsu" and "dattebayo" to the end of everything they say, many will find their view of the franchise tainted so that they either dislike it when they do watch or immediately hate it without even giving it a chance. Sadly, to those who haven't seen or read the series, or those whose views have been tainted, one of the first things they'll think about when they hear the word "Naruto" is not the well-constructed plot, the engaging battles or the impressive characterisation, but instead the crazed fans who make you ashamed to watch the show in case someone mistakes a simple fan for a complete Narutard.
As to whether individuals consider this behemoth franchise as being overrated or undersold, well that inevitably comes down to your own experiences and mindset. Personally, I think that the negative reaction to the publicity and adultation the show receives from both the industry and fans alike overshadows what is actually a genuinely good story. Sure, the anime isn't the amazing masterpiece that some make it out to be, and I certainly worry about those who claim that "Naruto is their life", but I feel that there's been so much prejudice surrounding the fandom that those new to it don't always give it a fair chance. I've experienced this with my best friend, who eventually picked up the series after my insistence that "he'd love it". He went into it on the back of irritation with the hype, never really gave it a proper try and dropped it after eight episodes focusing on small details to the point where they became genuine hatred. A couple of years - and many "Naruto sucks!" comments - later, myself and another friend convinced him to read the manga. He then powered through to the timeskip where he has now picked up the Shippuuden anime and is really getting into it (well excluding the filler that is) and finding the main plotline genuinely impressive.
My advice to anyone out there considering picking up either the anime or manga is this: try to forget everything you think you know about Naruto. Ignore the fans that froth at the mouth with the site of every kunai and forehead protector. Ignore the people who claim it sucks without giving any justification. Don't expect a masterpiece, and don't expect a steaming pile of crap. Instead, go into it with an open mind. If you do, then you may be surprised.