I made the switch to OpenOffice a long time ago. At least 10 years ago. When LibreOffice came out and it was clear that it won the heart of so many developers and businesses, I switch too.
LibreOffice is improving with each release and it is getting better. It does have some bugs, particularly the Writer with formating.
At the moment of writing this blog, I was using LibreOffice 4.4.1.
LibreOffice Writer ***
I use it all the time. It works ok, but I would like to make use of styles all the time. Unfortunately, I find them buggy and/or unintuitive.
Twenty years ago, I had the opportunity to use FrameMaker and that is what Writer should aim to become. Like many tools such as Latex, FrameMaker let the author concentrate on the content instead of the format since it is heavily based on styles. The beauty of FrameMaker is it still remains a beautiful WYSIWYG tool, showing the end result on screen live.
I often have to battle with the formating. Often it gets screwed up and it is hard to fix, even in some cases impossible.
LibreOffice Calc *****
This is the best piece of LibreOffice. Never suffered of any bug with it, except with OLE Writer documents. It is solid, with practically no bugs. I read that it lacks features that MS Excel possess, but for my casual needs; I never encountered any limitation. Please note that I do not make use of macros and I seldom have to convert spreadsheets in/from Microsoft Office format (.xls*). However, I never had problems with spreadsheet conversion.
It is an example for open source projects for robustness.
LibreOffice Impress ****
A few years ago I had problems with its ancestor, OpenOffice.org Impress. I do very little presentations. My kids however have created some and they converted very well to PowerPoint. I guess it is a good piece of software now.
Cannot pronounce on it since I never used it.