Typing /bongos brings up the configuration screen. From there, it's a simple matter of turning on and off what you want to have on your screen, setting the size and transparency, and moving the bars to where you want them.
By default, bar 1 will change with your stance (rogues and warriors, I'm looking at you), and the easiest way to load up your skills is just to shift stances, and then drag and drop the skills you want to use in that stance into the action bar. This allows for a very clean interface with a minimal number of buttons, if you're into that sort
You can also choose to hide the menu and your bags, really allowing for some leverage in cleaning up your UI. Take a look at this screenshot, the bongos bars are in the bottom right corner, freeing up a lot of space for other mods and UI elements.
I've noticed something quirky in my usage of Bongos, and this may or may not apply to you depending on your play style. I'm a big fan of putting my main actions as 1 to 6, shift-1 to shift-6, and ctrl-1 to ctrl-6. This way I can have 18 different actions or macros attached to keys within easy reach. To do this, I set my Key Bindings for the secondary action bars (Blizzard's left and right bars above the main action bar). I expected Bongos to set 1-6 on bar 1, shifted numbers on bar 2, and controlled numbers on bar 3. It doesn't. Bar 1 is alright, but shifted numbers went to bongo bar 6, while controlled numbers are on bongo bar 5. A little weird, but I just turned off visibility for bongo bars 2-4, and moved bars 5 and 6 around, so that my bottom bar is 1, middle is 6, top is 5. Again, your mileage may vary, and you can actually set key bindings for each of the bongo bars separately through the Key Bindings interface.
You can avoid this little headache by using Bongos' "Bindings" option from the Bongos config menu. All you have to do then is mouseover any button and press the key you want to assign to that button. This is a fantastic new feature that only lets me add accolades to this great AddOn. (Big thanks to Elizabeth Harper for pointing this out to me!)
So, while there are some quirks, I've found Bongos to be incredibly easy to use compared to something like Discord Action Bars, though not as infinitely customizable. If you're looking for a clean, low-memory replacement for the default action bars, you can do no better than Bongos.
Post your experiences with and questions about Bongos below and I'll do what I can to help you along.
Download from: http://wow.curse-gaming.com/en/files/details/2003/bongos/
Current Version: 6.12.13
Category: Action Bar Replacement