iStats Menus comes with a 14 day free trial. After that the menu items re disabled and show broken icons - easily fixed by registering it, in which case they change back to displaying info again (so you don't need to uninstall then reinstall if you choose to purchase it).
iStat Menus take away much of the "what's my Mac doing?" because I can easily see what the key parts of my Mac are doing. It is my No.1 utility friend, bar none, and can't do without it now - it'd be like driving a car without any instruments – speedo (Disk), tacho (CPU/GPU), engine temp (Sensors), electronics/fuses/computer (maybe Network).
I'm not one to watch my temps, but I have always been interested in finding out why my Mac has stalled or appears sluggish or slow or how my graphics card is going (CPU/GPU), slow to read/write data (Disks), if network activity has slowed or I want to know how fast my network connection is (Network), and how much ram I'm consuming (Memory).
So if you're not a gauges person, or if you're not mechanically minded, I can understand you might not be interested in all this info. Try it out and see how you like it.
Note: I am in no way connected to or employed to promote iStats Menus. lol