Came to Serendipity twice while on vacation in Vegas with my European honey and I can say it didn't live up to our expectations on our first visit so we went again hoping that we'd enjoy it more the second go around. Sadly, we didn't.
On our first visit we got the White Chocolate Frozen Hot Chocolate to share which was good, but not worth the $11 price tag. Next we each got BBQ & Blue Burger which was flavorless and had insufficient BBQ sauce on it. This visit receives 2 stars.
On our second visit (we were drunk) we got the All In Nachos and Pepperoni & Sausage Pizza. The nachos look delicious, but they taste so-so. I was really bummed that they just put melted cheese on the nachos instead of using nacho cheese (cheese whiz). Also, the chips underneath the top layer were pretty much missing all of the "All In" toppings so we were just eating plain chips. Thankfully, the Margherita Pizza was good so kicked the nachos to the side and feasted on the pizza. This visit receives 2 stars as well.
If you want to try Serendipity I recommend coming after you've had a few drinks so you won't be pissed off about dropping $70+ dollars on a so so meal.