First off, I would say take a test drive (obviously). I find the SelectShift to be fun, but I also live in an area where we mainly have flat land, but I do travel, so I can't wait to take it to the mountains.
As for being disappointed, this I think is really more of an opinion. Just because I (or someone else on the forum) may like the Focus doesn't always mean that you will to. I'd say, see if you can take it out for an hour or so and drive on different roads/ settings... play with the SST a little and see if you like how it works. Then compare to what you have and weigh things out.
Me personally, I needed a car regardless, and I've had Focuses before (some of which I wasn't too pleased with) but absolutely loved the 2012 (and was a bit glad that they decided to make the newer ones based on the Euro Focus).
So my two cents: test drive and see for yourself. Be advised that the SST is available on the SEL and Titanium as standard equip, and an option on the SE model (which is about $810 MSRP because you have to get the SE Sport Package). And LIke I said, I like mine so far. I think it's also a nice option to have for those times where you may need to control the trans a bit more than the computer does, but you'll pay a premium price for this option....
As for the hatchback, I'd say go with it. The sedan is cheaper, but the trunk is limited on space (and the actual height of what you can fit through the trunk is only about 24 inches. The hatch has slightly more cargo space, and it's easier to get things in and out of it. But again, the hatchback costs a little more.
I'd say choose what you want, but (and I'm assuming you're getting a loan for it) keep in mind that while the hatch is about $600 more than the sedan, over a standard 5 year loan at a modest interest rate, you're only talking about $10-12 per month extra. At least for me, that little extr wasn't a big deal. To some, it may be. I figured I might as well pay an extra $12 a month for something I like to drive than be paying for a car I don't really like as much. If trunk space or looks aren't really a big issue to you, then I'd say get the sedan version because it is slightly cheaper to purchase.