Winter '19 includes a great new feature for all users: choose the Display Density that works best for you in Lightning Experience.  We heard your feedback about changes you wanted to see -- more information on the screen, less 'whitespace', enhanced text contrast.

Please give us your feedback - especially as you check out the new Compact view.   We're not stopping here and will continue to enhance the UI each release -- your feedback helps guide us.  And as a sneak peek, we've started working on a "Dark Mode" option which we're really excited about.  

Release Note:

https://releasenotes.docs.salesforce.com/en-us/winter19/release-notes/rn_lex_display_density.htm

Developer blog post (but everyone should check out the intro section, which has a nifty comparison screenshot showing Salesforce Classic vs. Lightning Comfy vs. Lightning Compact view for the same record):  

https://developer.salesforce.com/blogs/2018/08/new-density-settings-for-the-lightning-experience-ui-in-winter-19.html

Enjoy!