Yes. Sure she's not in the same academic circle as Leonard is, but she's smarter than him in other ways. She's better in social situation and is more in touch with the world outside of the geek circle he lives in.
Leonard's constantly surrounded by people like him at work, and his friends are the same as well. It's nice to have a partner that's different to you because they give a new dimension to your life. If he was with someone that did the same as him, his life would continue in it's small bubble.
Penny is also quite adventurous and has helped Leonard try new things. He's quite timid and cautious, so it's good that there's someone to push him out of his comfort zone. Not in a mean way either.
I would say she's quite kind, she's taken on a motherly role with Sheldon, and I'd say that takes a lot of patience. On that note, she's a good partner for Leonard because Sheldon is his best friend, and I imagine many girls wouldn't be able to put up with Sheldon at all. She's not once asked him to give up his friends for her. In fact, she fits into his friendship circle really well, despite everyone else being different to her.