Back in July of last year, Valve launched Steam Labs, a way for interested users to test out various experimental features. After gathering feedback, the company would take what it had learned and apply it to the main website. That's exactly what's happening with Search today.
By way of the Steam Labs experiments, you are now able to use a slider to specify a price for the games you're searching for. Unfortunately, it's not fully customizable, as it goes from 'Free' to $5, $10, and so on in $5 increments until it hits $60. After that, there's an 'Any price' setting, which essentially means unfiltered. It is worth noting though that there's now a 'Special offers' checkbox, which will only show you discounted titles in your selected price range.
Beyond that, you can now include or exclude certain tags, and you'll be shown exactly how many entries there are with each tag. The relevance algorithm will place more emphasis on the tags themselves, so you're more likely to get results that are in line with your filters rather than results showing popular titles with a specific tag.
Staying a little longer on the theme of exclusion, you're now able to exclude VR-only titles, so if you don't own an HMD like say, Valve's own Index system, you can check out games that have VR support, but don't explicitly require it.
More results will now automatically load when you scroll, instead of you having to click through pages. When you decide to click on a specific game to check it out, Steam will remember your position in the list of results and when you navigate back, you won't have to scroll again to get where you were. If you don't like this behavior, you can go to your name in the upper right hand corner > Preferences and then scroll down until you see 'Search options'. Here you can disable infinite scrolling, as well as make sure that items in your library, on your wishlist, or that you've ignored do not show up when you perform a search.
One final quality of life improvement concerns folks using Steam in a language other than English. If say, you're using it in French, the 'Narrow by language' control will be positioned closer to the top of the search page, with your chosen language as the first one shown.
All these Search features are available now, and if you want to check out the current Steam Labs experiments like Micro Trailers or Play Next - which lets Steam recommend unplayed games in your library you should tackle next - make sure to head over to the dedicated portal.