Well, here's where my train of thought comes into play...
please remember that this is my opinion and you can do with it what you will...
what type of brewing do you want to do? do you want to brew a large amount to share with family, friends, and dare i say co-workers? or do you just want to do this on occasion and see where it leads...
I look at it this way, if you are the type of person to commit to things and then fall out of commitment, then the Mr.Beer kit may be a good investment for you. (Like the time I bought my wife and I kayaks, used them all of 4 times and then they now collect dust...)
I recently purchased a Mr.Beer kit thinking, "i'll give this a wirl." after looking at the box and such i figured it wasn't to complex and I'm sure it's not too hard. (and the kit was only $40, so if I use it once and then decide brewing isn't my thing... well then at least I didn't spend a lot more money and then fall out of interest).
I decided to give brewing a chance this morning, so I cracked open the box, set all the parts out and began reading the instructions...
If you follow all the directions and follow them to the word, it's not hard at all, even if you super analyze it and overdo the cleaning and sanitizing and do just as the directions say... it's still not that hard.
I've enjoyed the beginning stages of brewing, now my wort is fermenting hidden in a dark cabinet away from my wandering 1 year old.... and I honestly can't wait until it's ready to be sampled!
I decided that if this works out (i'll give the Mr.Beer Kit and some of it's recipes a go) and if it turns out I thoroughly enjoy it, then I'll be definitely upgrading to a more complex system.
I jumped into home brewing about a year ago and then for some reason I got side-tracked and I'm glad i didn't buy all that equipment b/c it would have gone to waste... I have decided to start out very small and let it run it's course...
so far so good.
like any investment, just think things through. best of luck.