TLDR: It's impressive, but not "I want you inside me" impressive. Unless you're wealthy.
In general, it is said that attractive people are more intelligent (surveys). These traits have a positive correlation. However, this is analogous to the chicken and egg problem. Are attractive people just more intelligent because of their attractiveness? Or is intelligence is what is making these people attractive? Also, there may be additional factors at play.
Using the theory of evolution, we can argue that an male's genetic quality is what attracts a female to a male (sexual selection). These "high quality" genes are indicated by physical attractiveness. And, since intelligence is also heritable and an indicator of genetic quality, these genes will be passed on the as well.
However, remember that this is all theoretical, and the studies were done using surveys. The halo effect can cloud ones perception of who is intelligent and who is not. By simply being more attractive, such a person may be perceived to be smarter.
Another theory is what a lot of other posters have mentioned, having high status. This idea also has an evolutionary basis, as having resources indicates to a female that if she mates with this male, their offspring will have enough food and comforts to survive and reproduce themselves (the ultimate purpose of life). Women would be attracted to intelligent men not for their looks, but because of their status. Some folks may argue that this is not "real" attraction, but I differ with them because it makes sense on an evolutionary level. Yes, it is not "physical" attraction, but it is a biologically-driven attraction nonetheless.
One study: https://personal.lse.ac.uk/kanazawa/pdfs/I2011.pdf