Shrewd
Part of speech: adjective
Definition: showing clever resourcefulness in practical matters artful, tricky or cunning streetwise
Example sentence: I find that the Amazon comments often are exceptionally shrewd and insightful, so I'm not going to diss them. But you don't really have any guarantees that what you're reading wasn't written out of friendship or spite.
Astute
Part of speech: adjective
Definition: Quick at seeing how to gain advantage, especially for oneself; shrewd; critically discerning.
Example sentence: The problem with motor neurone disease is they don't know when it starts. People go into hospital having fallen but get wrapped up and sent away, unless they're seen by an incredibly astute doctor. It is only when several things begin to go wrong that it'll be diagnosed.