I agree, no block skill if its purely based on timing.
Because you could have a really good skill at actually performing the block, but if your in-game block skill didnt add up, you would still svck.
Depends on what block related perks they might have It'll also depend on balance decisions about how fast or slow the different weapons are swung. I imagine a big two handed hammer swing will be easier to time a block against than a manic bosmer with his wildly flailing daggers of deadly annoyance. It's also probably a lot more important to time the block against that slower two handed pile-driver.
I would hope that poorly timed blocks still still damage related to the shield/weapon and your skill albeit a fraction of what a perfectly timed block. If timing is used to determine effects like skillfully away the attack (and very briefly interupting/staggering them maybe) as well as the degree of damage reduction out of the maximum based on your skill and shield type then I don't really see a problem. It makes the shield less boring to use and rewards you for using it well. I'll have to wait until I see what kind of shield related perks/abilities might be available. Norse and celtic warriors did a lot more stuff with their shields than just hold them out between themselves and the other guys point sharp bits. http://www.youtube.com/watch?v=7-Ms9RMH7IA Heck the Norse round shield was designed to pivot freely about the hand so it could be used to deflect an and brought about as part of a lunge attack. They could be used in a way not dissimilar to how defensive daggers like a main gauche were used - just with more emphasis on the defense.
More importantly - if they actually let you use a shield like the Norse used shields it'll be more fun. It would be hilarious if the right perk or two could let you bash things to death with shields. I would rather be able to do things with a shield besides have it be a sheet of metal I hold out when I take the "I take less damage now" button. The character skill should play a significant roll in how effective they are and probably determine what special moves/perks can be purchased that use a shield. At the same time I think providing an incentive for actively using the shield in a more challenging and thoughtful way than you would in a Zelda game is a very good thing. Sure, rhytmless people like myself should not find shields rendered useless, but if they be more useful and do more than just reduce damage then I'm all for it.
Of course - that has a lot to do with what kinds of special shield moves are available. If it's just a piece of 'I take less damage" sheet metal weilded to your arm then even with the challenge and reward for a well timed block I'll probably go with a spellswordy style of play - I'll use that dragon shout that throws enemies back as a more dramatic means of defending against attacks.