LaTeX is good for formatting academic papers and thesis with provided style files. Spelling check of LaTeX documents is never an issue by using a tool like Aspell or with the support of your text editor. However, grammar check still looks like an impossible task. For Windows users, this may be the most strong excuse to say Word is still better for everyday writing. Yes ... and why not use Word to do that task for LaTex documents? Word does not interpret LaTex, but how about RTF or HTML?
I have tried several applications converting pdf files to RTF including Acrobat professional. The generated files are messy. So I tried tools generating HTML. The one that I am using now is latex2html. Open the generated HTML files and let Word to spelling and grammar check them (F7), and then you can modify the tex file correspondingly.