As Elf arrives on the scene in ep.2, Zane is not impressed:

The third girl Masamune encounters is perhaps the worst, Yamada Elf, a thoroughly unpleasant, petulant, arrogant young author who couldn’t be more different from Masamune (or Sagiri for that matter). She lets her “#1 on Oricon” standing go straight to her head, believing she isn’t just the Savior of LNs, she IS light novel. Yikes!

As it happens, manga (which is derivative from LN, of course, but FWIW) gives Elf an in-source review in Chapter 31. Here it is, as translated by scanlators:

Chris: By the way though. This may sound a little biased, but I think my sister would be an excellent choice to consider.
Masamune: Eh..? Yeah, I guess.
Chris: You think so too, huh?
Masamune: Yes.
Chris: In addition to her good income, she's cute, she loves tidying up, her cooking tastes great, and she's fun to be around. I think she'll be an excellent wife. I'm glad you agree with me.
Masamune: (distracted by a creak)
Chris: Although she may not look like the type, I think she's someone who will devote herself to the person she likes. She's been praised as a very gifted girl, with talents from playing musical instruments to speaking foreign languages. I can even go so far as to say she's mastered almost all the skills it takes to be a good wife. All that was taught to her as part of our family's upbringing.
Chris (continues): Which leads me to ask you. What about my sister you aren't satisfied with?
Masamune: Umm... If I have to say it, it's everything else about her that you purposely didn't bring up in our conversation.
Chris (laughs): You sure know her well. Good answer. My sister's many strengths are all put to waste by her weaknesses. She never meets her deadlines. She's arrogant. She throws money about. She's afflicted with the incurable disease of chyuuninbyou, which is part and parcel of her talents, not to mention she's stupid.
Masamune: Yeah, she's stupid. But, I feel that both her strengths and weaknesses are two sides of the same coin. That stupid side of her kinda makes her cute, and her cringeworthy chuunibyou comments do make her look cool at times. We've had disagreements about attitudes towards work, but I did feel she had a point {about inspiration-based writing — Author}.
Masamune (continues): Elf is such an amazing person, it makes up for all of her weaknesses. She's an attractive girl. She's a dependable sempai. That's why I think I'm where I am now thanks to her. If I didn't already have someone I liked, then I probably would have fallen for her five times over.

The author's intent is fairly clear, I think. But it remains to be seen if anime is able to follow through on it.