I don't fully agree, although I fully appreciate jquery and it's application, it's just not something that I enjoy using.
While JQuery has an impressive library in terms of quantity, depending on how much customization you require on your website, functionality maybe limited thus using raw javascript maybe inevitable in some cases.
The JQuery javascript file is required to run JQuery commands, while the size of this file is relatively small (25-100KB depending on server), it is still a strain on the client computer and maybe your web server as well if you intend to host the JQuery script on your own web server.
I think users of jquery should always try to analyze the task at hand before choosing whether or not to use it. Sometimes the advantages will be greater than disadvantages, but of course this will be reversed in other cases. I'd rather my website was efficient to use than have jquery doing everything just to make my life easier at the expense of the user experience.
There's a time and a place for everything, and that includes jquery.