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

What: Shares of TripAdvisor (TRIP -0.83%) gained slightly in pre-market trading Friday after Susquehanna upgraded the online travel company from negative to neutral.

So what: Along with the upgrade, analyst Brian Nowak boosted his price target to $90 (from $67), representing about 10% worth of downside to yesterday's close. While Nowak isn't exactly bullish on TripAdvisor's appreciation prospects, he conceded that improving fundamentals are likely to limit the near-term downside.

Now what: According to Susquehanna, TripAdvisor's risk/reward trade-off is becoming more attractive. "We still think there are risks to hotel shopper growth, which is likely to continue decelerating given the more difficult compares," Nowak cautioned. "But with the company reaching 'meta neutrality' in December, shopper growth may not matter if the click-based revenue results end up being better than expected." Of course, with TripAdvisor still up about 120% over the past year and trading at a forward P/E of 45, I'd continue to be cautious about betting too much on accelerating growth.