Personally, I think he's a pretty strong hero, could use a few minor tweaks to make him seen more than 2 in 65 games. The number might be a little off since I play almost exclusively Tryndamere so my teammates can't pick him but thus far, I've seen him once on the enemy team and once on my team.
Quick run down of his Abilities and why they make me warm and fuzzy inside but leave a bitter taste in my mouth end-game when all is said and done.
Passive: As Tryndamere's health drops, increases critical damage up to 150%
I actually have never noticed a difference in my critical damage between 100% and 1% life left, is it bugged or is it just how I play tryndamere that it's not noticeable?
Bloodlust: Heals 135 and 65 for each Bloodlust stack up to 10 for a grand total of 785 health returned. Each stack of bloodlust increases critical chance by 4% and haste by 8%. The ability ratio on this is roughly between 1:5 and 1:4 so it's not even worthwhile to get an ability power item to make him heal a little more.
Why it makes me fuzzy At max rank it's got a 10 second cooldown so you'll always be pumping health back into Tryndamere. The only problem is it's omgamazing at the beginning of the game but the scaling due to the ability power ratio makes it not so omgamazing later on. Gives you enough HP after an undying rage to escape someone without a leap or snare or stun alive.
Suggestion: As it ranks up, add 6/3 health to both the main heal and the per stack heal respectively. This would bring it to 165 and 80 per point for a total of 965 which isn't quite half his HP in DPS set-up but would enable him to stay in the game longer earlier on and keep up when solo against ranged like Ashe and Sivir.
Mocking Shout Reduces physical damage by 20/40/60/80/100 and snares 20/30/40/50/60 when hit from behind.
Perfectly made ability, no changes necessary.
Spinning Slash deals 110/160/210/260/320 for a cost of 30/60/90/120/150 Health. Allows movement through impassable terrain attributing Tryndamere the Flee tag. (Shh don't tell anyone, it's my little secret)
Why it makes me Fuzzy The damage scales very well early on, enabling you to near-1 shot caster creeps at rank 3 and 1 shot the spectre minions (the life leecher ones) in the forest. It also allows travel through terrain which makes escaping a sticky situation very easy but it also can enable you to become stuck inside turrets where you end up looking like an ****** when it happens. Quickly ranked up, it gives Tryndamere a solo gank ability as all guides I've read attribute Tryndamere to getting this last. Used properly, you're capable of quickly farming up some cash to get items and then healing back to full while slowly chipping away at a champions health pool. Just run around in behind the caster creeps and sweep through them to your side, catch their champ if you can, dust yourself off and repeat.
Suggestion: Tryndamere is unique in that Mocking Shout costs nothing to activate and he has no mana required for his abilities. Why not go another step in the uniqueness and allows Physical Damage to buff his abilities along side ability power? Scale it way back as I frequently hit 300 physical damage in a game at the least so he doesn't become godly but just enough that his abilities scale up a little as he levels and gets gear but not so much that it's almost as if he didn't have this boost. This could also be extended to his heal. It gets to the point that this becomes purely a movement enhancement ability to escape or run down an opponent rather than dealing damage sometimes which should never happen for an ability.
Undying Rage - 7 seconds of immunity to death leaving Tryndamere at 1hp minimum during duration. Grants 3/6/9 stacks of Bloodlust as rank up and reduces cooldown from... I don't know what to 80 seconds.
This ultimate is simply badass in a can, especially at rank 3 as it brings Tryndamere to near max bloodlust (40% crit and 80% haste). Most champions will see you at low life and stay near to get the last hit which will quickly result in their death. It enables you to turret dive without worry of getting ganked by the turret and you become the best tank in the game for 7 seconds.
I see no reason to change this in any way.
Playstyles: I've seen two distinct playstyles on Tryndamere, okay I haven't seen but I've read about the other play style. Glass Cannon and Tank. Firstly I'll go over Glass Cannon because this is how I play Tryndamere.
Playing glass cannon, you sit at roughly 2.2k health at level 18 and full items but will have invulnerability to null this fact as well as 100% critical chance. Oh yes, I've had people at the start of the game ask me why I bother with Tryn cause he sucks and blah blah Jax is better etc. and at the end of the game they called me bull**** and said Tryndamere needs a nerf. Quite frankly, you have 2.00+ attack speed (2 attacks per second) and 100% critical with 25-45% life steal. Nothing can stand against you in 1v1, you're nigh unkillable in a group setting unless they work together to chain stun you in which case, you're dead because you have low HP.
This is what I believe Tryndamere was designed to play as and everyone playing him as a tank is doing it wrong. Yes he can have a lot of HP and still dish some damage, but why waste the money on health items when you can get an infinity edge early and be cranking people in the head for 600 damage crits?
Tank spec has it's merrits, you have a ton of health from Mog armor early on, lots of regen so you're hard to kill and have a 7 sec invuln in those "oh ****" moments. Tryndamere isn't meant to be played this way though, he's got far too high of damage and can crit way too hard to be playing like this. Plus, if his passive works, then you're making your crits do less damage when they trigger because you don't go down % wise as fast as a glass cannon.
With some changes to Spinning Slash and his heal to make them scale a little better past mid-game, I think Tryndamere will be up there in strength without being along the lines of 'a must have for every team' like Jax or any of the other currently really strong heroes seem to be.
Thoughts? Also, I'll write up a guide for him if you guys want since I see him so little and when I do, he does so terribly bad that I die a little inside.