While Fools should generally take the opinion of Wall Street with a grain of salt, it's not a bad idea to take a closer look at particularly stock-shaking upgrades and downgrades -- just in case their reasoning behind the call makes sense.

What: Shares of Priceline.com, Inc. (NASDAQ:BKNG) climbed 3.5% this morning after Goldman Sachs added the online travel company to its "Conviction Buy" list.

So what: Along with the addition, analyst Heath Terry raised his price target to $1,500 (from $1,200), representing about 35% worth of upside to yesterday's close. While value investors might be turned off by the stock's steady rise in 2013, Terry believes that there's more room to fly, given the strong tailwinds still working in Priceline's favor.

Now what: Goldman raised its 2014-2016 gross profit, adjusted EBITDA, and EPS estimate for priceline by roughly 5%. "We see increasing upside potential to our already above consensus estimates as we see Priceline benefiting from a European recovery, mobile traffic growth, and increasing economies of scale, particularly in customer acquisition," Goldman noted. "Priceline's mobile footprint, geographic mix, and critical mass of hotel relationships should continue to drive considerable long term competitive advantages." With Priceline shares still trading at a growth-relative discount to several of its peers, it's tough to disagree with Goldman's conviction call.