its always exciting to see new champs, but there seems to be a lot of overlap and most don't seem too original or innovative. someone commented that the last 5 have been ad and similar commando style human look with armor and a big weapon. I like the animations on jayce, I think there's some originality and complexity there, though strikingly similar to darius, garen, graves, etc, and a far cry from the uniqueness of anivia, malphite, fiddlesticks, and I can only imagine the overlap of their skins. I noticed a screenshot with "glacial malphite" (which will probably be similar to barnacle malphite) and dreadknight tryndamere which will be similar to the latest new champ ad skins which are "dark evil humans with big swords"
I look forward to new innovation and versatility/complexity and gameplay, I think jayce has some of this, though the extent of the spell effects seems lacking (his jump attack only knocks the enemy back for a sec, he has a yellow force field that seems to have no special effects, he walks through the laser and gets electric charge, though I think switching to cannon mode is cool, the cannon is kind of wimpy)
I'm not trying to be too critical, but I think jayce is one of the better new champions of those datamined, teek sounds like a ratlike hunter (twitch-warwick...dota's bloodthirster) that sniffs out the enemy, but nothing too special there, obvious abilities. a couple of them shoot missiles, like every other champ. I'd like to see something like dota's enigma ult, obsidian statue nuke, demon hunter's swap health ult, etc.
TL;DR not too impressed with the latest champ previews, but haven't really seen their entirety. they seem much too similar, at least considering the last 5 have been and the next 5 seem to be similar to each other or a champ already in game.