Well, I have a friend who started with Mr. Beer about 4 years ago, and STILL uses it and loves it. I do have her making small batches of wine, now, in 1 gallon glass jugs. She never wanted to do anything more than Mr. Beer.
I got a Beer Machine and used it ONCE. Before it was even ready to drink, I was making a real beer kit with an ale pail and carboy. About a year or two later, I went all-grain.
So, I guess only you can answer that question! Mr. Beer might be just the ticket for you indefinitely- or you might outgrow it right away. But at least you're not out much money while you decide if you like the hobby!
Broken Leg Brewery
Giving beer a leg to stand on since 2006