please explain. what would you change? how would you change it? why?

Not such a bad build, but far away from decent. Some versions of itemization are actually bad.

thanks man!

+1 for an actual tank Alistar build ( most I see are AP... )

yes and no. there are other ways to play him besides tank. i have a nice off tank build posted now, but if you try to ap him your ult becomes only an escape mech. if you want an ap tank i suggest Cho'Gath since everything he has scales with ap in a 1:1 ration for Rupture, a .7:1 ratio for Feast and Feral Scream and a .3:1 ration on Vorpal Spikes whick adds to his basic attack. also Olaf jarvin IV Wukong Garen ect make better off-tankers, although i wouldn't play then as tanks. the ability to screw an ad carry over by taking 1/20 of the damage they thought you would and slow their as by 55 and ms by 35 also shouldn't be over looked, especially with a good damage output. Just my thoughts. feel free to post your own builds with your own ideas. i'll be sure to view them.

also i'm now currently editing this build to show the 3 main ways to tank with him and how to off tank for all the people out there who want to.

the reson for the manamume as oppossed to the aa are a few. first, if you look at his ult, he gains ad. this can give him **** tons of ad for a tank. second, you don't need that much mana regen. and finally, he just got an ap nerf as riot just said NO AP ALI. and yes, there are other ways to play him. this is just my favorite. i was getting philo early on, but the lack of max mana is a huge problem. and while there are other ways to go for that, i've found this one the best in my opinion. and he does do damage. with a manamume and his ult his basic attack is about 250-300. the reason for the armor and mr still despite his ult is that THAT'S ONLY ON ABOUT 1/10 OF THE TIME!!! you need to still be able to tank. but that's why i didn't stack as much as i do for some other tanks. and Ignite, Feast, and others will still rip through you with your ult. also, i find it doesn't last long enough for most team fights. thanks for the feedback though. these are just my thoughts.

I like the idea of your build with the tanky heal spamer, allowing him to play multiple roles, but I disagree with parts of our build, namely ninja tabi and manamune. I honesly think the tear is better turned into an AA late game when your out of room, or just skip the tear all together and get philo for regen early

There still ARE other ways to play him besides tank you know.....
I'm just wondering if you're building him too tanky: he has an ultimate that makes him nigh-invunerable for 8 seconds on a minute cooldown or so. You grab a manamune at the end of your build, which could work. But Alistar still doesn't do any damage really, even with a manamune (especially for the cost).