Tekken 4 Yoshi is also great. He was more "invisible" than in any Tekkens before. True "yoshi" (good luck) because people couldn't hit me many times at all. He had exceedingly good mobility, and his BT was solid: he "knew" when he was in BT and when NOT. And so you felt that in tekken 4 you had a total control over Yoshi's actions. I loved the little, buggy but also powerful Yoshi there. If not Jin, he would absolutely rule this game.
Tekken 5 Yoshi feels as if he lost something. You're right, Raven, about the d+3+4 and b+1+2 moves. They SUCK sometimes. Especially b+1+2 (what a disadvantage on block!!!!!! >_<), and d+3+4 not only has poor range... Yoshi is vulnerable both just after this move AND during the execution! Can you believe this SHIT? (excuse me... but I'm getting nervous everytime I start to think about what they did to Yoshi in T5).
Tekken 5 is now even more PRECISE. And Yoshi's actions were just about taking advantage on the lack of precisive movements of your opponents. In the other words: tracking and overwhelming RANGE of opponents attacks can paralyse Yoshi's dance. His disadvantages on moves' whiff are devastating for his health.
Geez... I'm soon going to make a whole essay about this. Please... I'll make an article soon, I'll describe my feeling there, OK?
To sum up: I AM NOT SATISFIED. I AM DISAPPOINTED. DOT.