Yes she has been hyped many times being strong, I do believe that too, as for the senpai part well... It's not a suffix for someone being strong or anything like that, Senpai is like the elder student, while Kohai is the youngest student, Senpai could also mean mentor, but it's not an indicator of strenght, rather it is an indicator of seniority more or less (not totally seniority either)
Unohana's abilities are based on "Spirit Power" itself. Most likely, she can do all sorts of things with reiatsu. Technically, she is probably the most formidable opponent against the Quincy. Can't wait to see her Bankai in action too.
Why do you say that? We really don't know what unohana's abilities are so far and her actual shikai seems to be more similar to mayuri's. I mean, the creature we saw seems to be an organic animal much like mayuri's bankai and taking in consideration how bankai works so far what would make sense is that her bankai is just a bigger and meaner version of what we already saw assuming it even has battle applications. We also know because of the databook that unohana's forte is swordsmanship when it comes to battle. Unohana is almost certainly a great kido user but the case could easily be that she has heavily specialized in healing kido and not offensive kido... Using kido is not quite enough to make unohana a perfect counter for the quincy though and even if she actually was proficient at it it does not mean it will be enough for her to be a good counter to the quincy. Realistically only extremely few characters have shown the ability to use kido successfully in battle and as far as we have seen the only ones that could actually replace their special abilities with kido would be hachi and tessai. Byakuya has used kido in battle but it has been just a few spells which add something very specific to battle and by no means comes close to replacing his abilities. Aizen was able to use high level kido but even his 90th level kido required an incantation for it to be worth something(without an incantation he barely reached a third of his true power). Urahara used a kido but when it came to battle he ended up relying heavily on his sword so I would argue he can't use kido to an extent where it would be a more practical than his sword. He is like a refined byakuya. To be completely honest I can't imagine characters other than tessai and hachi even actually having the skill to use kido in a way where it alone would pose a threat to high level quincy.
I think that the best indication of Unohana's power is her confrontation with Aizen. As we've seen, he doesn't hesitate to strike down Hitsugaya or Kommamura. Yet, he withdrew when Unohana came, only accompanied by her vice captain.
No spoilers outside Spoilers thread.
Overall, it is more of an indication of kobo contriving the whole thing; he needed the rest of soul society to find out about aizen, so he used Unohana and isane. He couldn't take them out of commission.
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Unohana is currently the most powerful captain in Soul Society. Only Aizen and Yama exceeded her battle stats (560 vs 540) in the original issue of captain powers in the manga...also Kubo in the timeskip interviews stated that Minazuki has a battle form, the creature is not how she fights, I doubt her bankai is therefore as someone hinted, a giant sting ray....she is also a kendo master. There is no question about whether she can kick ass. it's only a matter of when and who's.
Ha! The explanation's in this chapter! A kick in da face to ppl complaining that Bleach is full of plot holes and asspulls!