It's also a handy tool for the international tourist, with users leaving feedback on everything from the quality of the eggs at Las Vegas casino breakfast buffets to the lines at Paris's Musee du Louvre.

Yelp's users are, primarily, an enthusiastic and appreciative bunch.

"Michelangelo, you really outdid yourself," user Kathryn W. of Long Island notes approvingly of the Sistine Chapel, in a characteristically positive review.

But for a small but vocal minority of Yelp's unhappiest travelers, the world is full of disappointing discoveries.

Such as:

Museums are full of art

Musee du Louvre, Paris: "Each to their own I guess, but paintings and sculptures just hold little or no interest for me." 

-- Andy, Nottingham, UK

Metropolitan Museum of Art, New York: "I refuse to pay any amount of money to see antiques collecting dust." 

-- Anthro Food E., New York City

Old things sometimes look old

New York's Statue of Liberty: "As a proud American I wanted to love this, but was grossly underwhelmed... Old Lady Liberty is just that... old." 

-- Nicholas H., San Francisco

Rome's Colosseum: "Yes, it looks great at night but put some lights up on that abandoned GM Assembly Plant in Detroit and you'd have about the same thing without any long visitor lines." 

-- Marqus R., Ft. Lauderdale, Florida

Istanbul's Hagia Sophia: "There is nothing much to see inside and the place is falling apart. I get that it is ancient but I have to ask where the entrance fee funds are going." 

--Camie T., London

This, by the way, is the interior of the 1,500-year-old former basilica and mosque in Istanbul, Turkey. We guess some people just have really high standards.

And a lot of the world is just ... meh

On the Vietnam Veterans Memorial in Washington, D.C.: "It's a wall with a bunch of names on it. I mean NO disrespect but spice it up a bit. It's kinda boring." 

-- Gina M., Philadelphia

On the Eiffel Tower: "Crowded, overrated, and ugly from up close." 

--Emma F., Alpharetta, Georgia

On Rio de Janeiro's towering statue of Christ the Redeemer: "I'm not sure what all the fuss is about." 

-- Stephanie T., Rohnert Park, California

Nature, it turns out, can be a real bummer too

Like Yellowstone National Park:

"I want to tell you that I am not some nature hating guy. I take my kids hiking. I rock climb. The problem with the place is that it is dull. [But] If you are in the area for some reason it is worth dropping by." 

-- Kahlil G. Bethesda, Maryland

Or the Grand Canyon:

"As amazing as the views are it is really kind of boring. Every 500 ft a new vantage point of the same thing: a really big hole in the ground...What would [be] nice is segway rentals." 

-- Brad M., Englewood, Colorado

Or Yosemite National Park:

"As another reviewer stated in one word, this National Park is a 'cluster[expletive].' I couldn't agree more." 

-- Misty P., Kapolei, Hawaii

Disgruntled foodie tourists have a particular flair for the dramatic

See David N. of New York City on Dinner by Heston Blumenthal, a swank London eatery:

"This meal brought to mind the fable of The Emperors New Clothes, as we are encouraged by the fine artistry of the menus text to be inspired to indulge in the rich tapestry of delicious cuisine, only to discover that the meager over salted portions fall lack-luster on the palate and at times verge on the inedible.

"The only diversion to this was the frequent sound of smashing glassware and east end babble. All round disappointing and way, way overpriced."

Or, more tersely, Debbie C. of Arcadia, California on the $250 tasting menu at the Copenhagen's NOMA:

"One of the courses literally made me gag but in NOMA, spitting into your napkin would be a like crime so I swallowed it like a bitter pill."

Some possess sophistication the rest of us can only dream of

"After seeing so many other free churches' beautiful ceillings, I was disappointed with the Sistine Chapel's ceiling. 

-- Chun P., San Diego

"I visited about 5 of the [Smithsonian] museums and barely LEARNED anything. It was more of an exhibit of seeing "stuff" added with 1-2 sentences written in a 3 graders level. I understand a lot of foreigners come here but I feel like it should still provide some level of sophistication."

--Andrew W., Atlanta

And others, um, don't

"I was walking around the [Eiffel] Tower when two young girls asked me if I was an American, and then asked me to sign a form to support the International Association for Deaf Mute and Homeless Children.

"I said sure, I'll donate 10 euros. I gave them 20 euros, and then [they] said the min donation was 20 Euros and wouldn't give me back my change.

"Then they said, 'give me another 20 and I'll give you back two 10s.' Well, stupid me! I gave them another 20 euros and then they started laughing while they walked away.

"I think they were Turkish." 

-- J.M., Boston

(CNN)