I haven't counted the number of packages I use, from MELPA, but it's likely around 100. I have problems associated with MELPA about 2-3 times per year.

One of these times was yesterday, when cider-test was added to cider. Melpa excludes files ending with -test.el by default, so a file was missing. I grabbed the file manually from github and went on with my evening. An hour or so later the pull request fixing the problem was merged.

For developers, the criticism against MELPA is just FUD. If anything goes wrong you can fix it easily enough.