What I like about it is that it does, I think, achieve its goal of being simple. All I do on a fresh setup is hide most of the bars (a quick shift-right-click in config mode), move the class and pet bars to a reasonable location, and bind the keys (you do have to do this; leaving your keys bound to Blizzard action bars are just going to confuse the mod). I just learned today that /kb will put you in key-binding mode.
Make sure you don't hide your roll frame, though, unless you have a replacement for it; I did this my first time through and couldn't figure out why I wasn't being given the option to roll on items. I also like being able to fade bars when the cursor isn't over them; this is handy especially for class bars on aura-type classes (DK, paladin, hunter) where I change auras only rarely.
Another Dominos feature that I enjoy is being able to bind keys directly to a spell in your spellbook, without having to put that spell on a button. For instance, on my priest and druid, control-R casts Resurrection/Revive. Caveat: this binds to a particular rank, so make sure you re-bind it when you get a new rank of the skill; this issue led to me using rank 2 Binding Heal for quite some time after hitting 80.
By design, Dominos lacks features for things like cooldown counts and range coloring. Fortunately, it works seamlessly with other mods to do these things: OmniCC handles cooldown counts beautifully, and RedRange is a good drop-in range colorer (all it does is turn buttons red when you're out of range). ButtonFacade is also very handy for customizing the look of the buttons, although I prefer the default look (as seen in the screenshot at top; apologies for the JPEG muddiness).
Download Dominos at WoWInterface