1. The LiveReload feature stops if you open Chrome DevTools, which I often use to debug. Unfortunately, Brackets' own tools aren't enough to match Chrome DevTools, so I have to work with the LiveReload feature turned off, which is a bummer. I really really hope they fix this.
2. We use LESS at my job, and while there are LESS autocompile plugins, working with LESS in Brackets is still not as seemless as working with CSS. However, I think that with some better plugin support and some tweaks to the current plugins, it eventually could be.
I've got to say though, Brackets has totally replaced Sublime for me as my primary editor whenever I'm working on front-end stuff. Theseus and the other Javascript debugging tools are top-notch. I recommend that any front-end developer at least give it a shot for a week or two.
Personally I've gotten in the habit of switching back and forth. I tend to use Live Preview when I'm tweaking layout and design (so much easier than doing things in the inspector and then remembering what changes to reflect in my code), but switching to the browser tools for most script stuff. If Live Preview had a javascript console I suspect I'd hardly use the browser tools..
https://github.com/njx/brackets-livedev2
We haven't decided on how to handle things like Theseus yet.
Dart has the same issue I believe when connected to their dartium browser.
It's nice, it is a fair bit quicker then Atom (which just seem really sluggish on my system).