I'm not a big fan of the 'all in one' tanks either, but it can be as good a place as any to start. Personally I started with a 30g tank I bought at a garage sale in our neighborhood.
This is a difficult hobby for a variety of reasons. It seems that about 2/3rds to 3/4th of all the people who get into the hobby end up getting out within a year or two. A) It can be VERY expensive, even if you buy good used equipment. And having backup equipment is also expensive. B) A lot of people get frustrated with dying fish and dying corals as well as algae and bacteria blooms. C) Lots of people get tired of doing the very regular maintenance their system requires. D) There is also the making RO/DI water to top off your system and making saltwater to do water changes. E) Then there is the plumbing, the electrical load, the chemistry. F) And the constant learning new things and upgrading to new equipment. G) Oh, and then there are the leaks and spills! LOL!
But if you stick with it, this can be a very rewarding hobby. I had a 30g tank for about 2 years, Then I had a 75g tank and a 35g display refugium for about 3 years. Then I upgraded to a 180g mixed reef with a 75g hexagon tank beside it over a 180g sump/refugium. A couple years ago I added a 65g shallow reef and a 25g frag tank, so now I have 4 tanks!
But I've made some very good friends in our local aquarium club. I
HIGHLY recommend you look for a local club and there is a list of them here:
http://www.reefcentral.com/forums/forumdisplay.php?f=80
And whether it's local club members who come over to buy coral, or friends and family who come by, everybody likes the aquarium and many are just fascinated by it. I enjoy having a glass box full of my little part of the ocean right in my house. I can't go to outer space so I'll have my own little alien world with lots of strange critters from the underwater world.