This is something worth pointing out - the Essentials doesn't change anything that you like about 4e.
I don't want to say too much, since we have more preview articles coming out, but if you decide you don't like anything in the Essentials you'll still have plenty of new books, interesting options, and so forth to look forward to.
To pull the key sentences from the article:
"If you’re already playing a Dungeons & Dragons game, there’s one very important thing to remember—the Essentials products matter only as much as you want them to. We very carefully designed the new classes and added more options to the races in such a way that existing characters remain unchanged."
It was critically important throughout the design process to make sure that the above statement was true.