Your opinion of Wikipedia's quality depends on what you focus on. For a project with more than 5 million separate entries, summary statements are very difficult. What's more, any such judgment cannot remain fixed. This is because, as an essay declares, "Wikipedia is a work in progress". Or as the frequently-invoked shortcut to this page says, Wikipedia is WP:NOTFINISHED.
And Wikipedia will never be complete. Even if the creation of new articles slows (and it hasn't much) as there are new discoveries, inventions, and scholarship, and as current events march forward, new articles will have to be created, and existing ones will have to be updated. Sometimes articles can get worse, but also sometimes this isn't because the article changed but because the standards for what makes a good Wikipedia article have changed.
The writing of Wikipedia is the summary of all human knowledge. There's a future in it.