Koji Igarashi's probably a really nice guy; prolly quite smart too. I could see him being a pretty cool dude to hang with (so long as he took the damn hat off first).
However, I think he is past his prime. SOTN was his magnum opus and I just don't think he can personally top it. (That doesn't mean someone else can't. I say let the former head of KCEK give it a go again, if he's still around). As such, IGA's Castletroids have really only gotten more predictable and trapped in their element; that being to try to match the overall grandeur that was SOTN but just never quite reaching it.
But he doesn't have the same talent in his team anymore, or if he does, they are stretched too thin. The proof is in the constant downspiral in the art department and the general lack of polish as he seeks to make the castles larger, the systems more complex and just this going with the general idea that more begets more.
He has made some awesome contributions to some of the sub game systems in both the 2D and 3D outings. I love all the replay value he manages to get into a game. I think more than a lot of his peers, he is successful at this. His equipment switch (character switch, in POR), his weapon-building and his constant ability to give us secondary quests in some form is also an impressive trait as a developer he has upheld.
You really can't complain about how he has kept the series alive this long, and consistently makes decent, fun games. Also, he hired two very talented female artists and they have done just as much to shape the identity of Castlevania today.
But I hate his story telling, and his more an more lame excuses to cover his tracks due to bad, sloppy writing. I can't take the story seriously anymore, and at least before I didn't have to because there wasn't much there. Game's don't need stories -- Mario is proof of that -- but if you're going to attack something as potentially complex and ambitious as a milennium-running story arc, you better be ready and confident to do it. Yeah he at least tried to make something of it all, but it's just not working for me. I already would like to see some of these plots redone, actually (LOI in particular, and I think HOD needs to be retconned due to retarted, boring characters and lack of an interesting plot at all... made for a cool twist as far as the castle goes at least).
He started something interesting with Soma and the concept that Dracula was never going to be what he once was. Soma's not necessarily an interersting character though, and the endings to the Sorrow games come off as sappy and trite compared to what could have been the ultimate showdown of good vs evil. Especially in DOS, that DBZ/Sailor Moon friends save friends with LOVE -- ugh -- CRAP! Hey I'm all for throwing the power of love into the mix, but you gotta be more clever and subtle than that. The series deserves nothing less. I dunno... maybe he's not done with the Sorrow part yet though.
I also really don't understand how he's so horrible at developing an accurate 3D castle. Capcom's done it 4 times now with its Devil May Cry series. We all thought LOI was just a baby step for the series and forgave it at the time, but when IGA gets a second chance, and he blows it even worse, it's not a good sign that he's up to the task. And even HE admits it. COD was trying to be too big and as a result a lot of corners were cut in design to get there. I am worried that Order of Ecclesia might suffer a similar fate.
I just think IGA's time at KCET is drawing near. He doesn't seem to have much more innovative ideas left in him, and maybe KCET as a whole just needs to try something different than the SOTN formula anyway. We saw interesting potential in how they handled the Rondo remake (and yes I'm also thankful he gave us that).
It's not just IGA, if Konami really wants to grow the series, than they have to grow the funding with it. More funding would also allow higher talent, and someday even a better producer. I'm not saying IGA necessarily should be cut from Konami, but if you want to breathe some fresh air into Castlevania, let someone else have a go at it. IGA wants to try other series anyways.