What are the impressions of Jayce so far?
Granted, I'm still low level (hooray, no runes) so keep that in mind but ... his early game is amazingly bad. His base stats are really low so the early farm is important to secure an early Doran's or two to get his AD somewhere respectable. I've tried Q -> E -> W and W -> Q -> E starts and not sure which I like better yet. Q start gives better zoning options but the damage isn't that great at level 1 without an E boost while W start lets you punish over aggressive people by triple auto attack on them.
Damage wise, he's got really good burst surprisingly. I mean, I expected it to be a lot worse than what it's been since he lacks an ultimate finisher. But, Cannon E -> Q -> W -> switch to Hammer -> Q -> W -> E (weave in auto-attacks of course, etc.) is an absurd amount of damage late game since he scales really well. And since his cooldowns aren't that bad, you can just swap back to Cannon when you're done with the combo and pop his W again to get some ranged burst down on someone.
Right now, I've been building him with the idea of maxing W early and forgoing Attack Speed items since it's only a 6s base cooldown when maxed and it gives you 2.5 APS right there. Q after lets his Cannon E -> Q punish hard and even his level 1 Hammer E still hits for 8% MaxHP base. Early Frozen Mallet helps pursues and gives him the HP he needs when in Hammer mode and I'm undecided what I like better for him after that. Just been doing BT since it's a solid item :|
Honestly, I like him better top as he'd be a respectable bruiser in just Hammer mode so Cannon is just there as a way to let him poke and control the lane.