Is Sparrow a better Bitcoin wallet than Electrum?
I haven't used Sparrow yet, and I'm pretty happy with Electrum.
Is there any great feature available in Sparrow that is not available in Electrum?
Yes. you can CoinJoin your precious bitcoins in Whirlpool, arguably the best CoinJoin implementation to have ever been created. Additionally you can use: PayNyms, payment codes that you can use to prevent address reuse; stonewall and stonewallX2, fake and real 2 person p2p CoinJoins, respectively; and StowAways, which are simple Payjoins.