Sure, let me try by comparing it to the competition: the firefox devtools, firebug and opera inspector (I haven't used anything else). I'm using the chrome devtools for DOM inspection (HTML and SVG), CSS development and debugging, javascript repl and debugging (and via node-inspector also for server-side debugging) and HTTP profiling and protocol debugging. So I'm using it primarily for web development but its also an invaluable tool for web scraping where you can just copy&paste xpath expressions from the dom inspector for instance.

The Opera Developer Tools (Opera Dragonfly): The UX is done well, the markup editor works even better than in chrome and I like the screenshot utility and color picker. The css inspection is inconvenient when you want to change properties or add new rules. The network log is done well but the UX can become confusing, the make request feature is exceptional I don't know any other devtool that has that integrated. No xpath in the dom inspector.

Firebug: This was the first browser devtool afaik so it has a long history and years of development behind it, I always considered it to be "the firefox developer tools" and I was really surprised when mozilla announced they would recreate it on their own instead of just integrating firebug. But I guess they have their reasons.

Firebug has a great UX, everything is fast and polished although it has become a little old, it still integrates nicely in the current firefox UI. The dom and css inspector is great, it allows to quickly change anything you ever want, with the exception maybe that you cannot add new css rules (only element styles). The network inspector is exceptional, best of all 4. I don't like the console/REPL but its alright. Overall still my second favorite.

Chrome Developer Tools: Provides by far the best UX and is clearly the most powerful devtool around. Its also the only reason why I have chrome installed, my main browser is and was always firefox. The css inspector is just great, you can update or add new rules and properties and it has great auto completion. I don't like the dom editor through, the edit as html feature lacks a bit. Javascript debugging and the console work exceptionally well and you can even edit and save your code within the devtools. It has HTML5 builtin features for web workers, indexedDB, local storage, etc. You also can use it to debug nodejs applications through node-inspector.

Firefox Developer Tools: I must admit, I don't even know where to begin. The UX is just awful: From the alien dark-blue that doesn't integrate at all with the rest of firefox and the font sizes that you can't change to the strange dropdown menu/button combinations in the latest version. The DOM inspector doesn't allow you to edit html directly, has no xpath and the css inspector is confusing and doesn't has autocompletion. There is no resources overview, no networking debugging and profiling.
I do however acknowledge there is some progress in the latest snapshots, I like the scratchpad, style editor and the UI overhaul made it a bit more usable. There are still no settings, still no way to change the dark theme. I don't say it isn't making some progress, but its so slow (they say they need a few months for the python api alone), that chrome will have progressed well beyond and I don't see them catching up.