Okay, so some quick thoughts on new preseason stuff so far.
New jungle items:
I'm kind of on the fence on this, the new Smite stuff is cool but to be honest I haven't experimented much with them in PvP yet.
Giant Enemy Crab (Monster on the River):
This thing is absolutely worthless. The speed shrine really doesn't do much, and a little bit of vision is cool...but let's be real. This thing takes so long to kill that it's practically ignored by both teams until well into the game.
Dragon Bonuses
Like the jungle items, I'm on the fence. The reason is, as I saw in one of my games, if one team gets ahold of 5 Dragons, they can have a massive gold disadvantage and still wipe the floor with the other team in teamfights. A team with 5 Dragon buffs is next to impossible to come back against.
Baron Bonuses
Stupid strong at the moment, so I don't really want to go too in depth. Hell, the super minion with Baron buff was tankier than the 6-item Sejuani we had to deal with. At this point, if your inhibitor is down and the enemy has Baron, you are going to lose the game. There really isn't much you can do. This will probably be changed.
Still Waters buff
I don't understand this since it's so out of place on Summoner's Rift. Can't comment much, but the vision over walls is cool.
Elixirs
I don't dig not being able to buy early Elixirs for that risky play. The Elixir of Wrath is cool though, AD casters that fall off late game (like Pantheon) will appreciate this. I haven't tried the other ones yet in PvP.
Righteous Glory
I don't really like this item too much...nothing says "I'm going to towerdive you" quite like this does. Not much else to say.
Will continue to toy with this stuff.
Overall, I loathe the season 5 changes so far. But it's WIP so meh.