I've been riding the Matterhorn these past couple of days.
The new Bobsleds are really nice. Rows 1 and 4 require you to sit with your legs folded, or however you can put them, in a small space. I'm pretty short, and it still felt awkward sitting in those two rows. The other rows are comfortable, they offer leg room for all sizes. You're feet are placed inside cubby holes and each side of the seat, and they're pretty deep. Each seat has grip bars on the side, but they are awkwardly placed and hard to hold. The seat belts are like those of Indie and Star Tours.
I've rode both sides of the mountain.
The Tomorrowland side is the faster and scarier of the two, but it's also not as smooth of a ride. It's very rough and jerks a lot throughout the ride. Harold is also super loud on this side and very frightening with the effects. It's not for the faint of heart or the little ones attempt to ride their first big kid ride. I've been on that side 5 times and I still get scared each time, even though I know he's coming.
The Fantasyland is obviously the mellower side. The ride is a lot more smoother and slower than the TL side--you won't have any whiplash here. Harold is also toned down and not too scary. It's defiantly the side to take the grandparents and kids on.
The mountain is set to open up officially Friday, but it may(just a maybe) have a soft opening sometime on Thursday.