Usopp, Luffy, and Chopper tend to be the comical relief a lot of the time. Usopp more so than Luffy. Usopp's cowardly nature adding more hillarity. For example, when they were on Drum Island and met up with the bowing bear, Usopp freaked out and immediately flopped into the snow telling everyone to play dead. He will also make hillarious faces during his cowardly moments making it even funnier. He also has a habit of 'putting himself on a pedistal', as the term goes. He will puff out his chest and start bragging about how great he is, and for the most part, people will believe him and cheer him on.

However, with his cowardly nature comes a strong sense of loyalty and morals. Though he may be terrified, he will join in the fight and fight for what he believes in. A prime example of this being in the Aarlong Park arc when he takes on the task of fighting Chuu. He has also taken on stronger opponents such as Mr 4, Miss Merry Christmas, and Perona. He also played an important part in the Little Garden arc, especially in his freeing of Zoro, Vivi, and Nami from their suffocating wax prison.

 

Father - Yassop
Mother - Bakina (???)

Usopp is a man of many talents, to tell you the truth.
For one thing, he is an extremely talented sharpshooter, able to shoot the out out of a far away weather vane. He is able to target with all forms of aiming equipment including slingshots, pistols, and cannons.
Along with this ability, he is also a talented artist and is the one resposible for painting the Straw Hat logo on the sail and flag of their ship.

He is also a very skilled inventor and dabbles in chemistry. He mostly uses this for his stars (slingshot ammo), creative projects, and more recently for weapon design. He is the one responsible for creating Nami's Clima-Tact and his newest weapon, the Kabuto. With the new addition of Franky to the crew, the two of them will often team up for certain projects such as the air cannon used against Oz in the Thriller Bark arc.

And of course, Usopp's greatest talent is telling lies. Although his lies are usually meant for pure fun (he will use them to try and escape danger sometimes), it has been discovered that some of his lies turn out to be true. One such instance was when the Straw Hats were leaving Little Garden and a giant goldfish showed up whose poops were so big they looked like islands. This was a lie he had previously told to his friends Kaya.

When the series first began, Usopp wasn't very strong and didn't have much in the way of attacks and weapons. As the series has progressed he has invented some weapons, mostly simple ones, for his own use. Though most of these turn out to be gag weapons, such as the '5 ton hammer'. However gaggish these weapons are, Usopp is a very tacticial fighter, using what he has and his surroundings to his advantage whenever possible. More recently, however, Usopp has become quite attached to a new weapon known as 'Kabuto'. It is a large slingshot attached to a staff which complements his sharpshooting abilities. When he obtained this new weapon, it became quickly obvious that his fighting abilities had grown. An example being when defending the Going Merry at Enies Lobby, he joined in with Zoro and Sanji by shooting down an equal share of the cannon balls fired towards the ship, sometimes three in a row.