Anyways, here comes a small rant about my first hour with it.
First impression are extremely impressive and a bit of a shock actually
The pads are different, but even better than the SP-555 ones actually... I like the soft but rock solid pads better than the SP-555's.
My SP-606 came with a whole bunch of samples on it already, so I've been able to quickly check a lot of things out.. Effects are good and overall it's pretty clear why the SP-555 isn't called SP-666. Basically I already heard here that the SP-606 is more advanced, but although not entirely comparable to the SP-555 perhaps, it's definitely going to be my main machine from now on.
The screen on it comes in very handy and I think that's basically the weakest point of the SP-555 if you'd want to compare them. I know having a screen or not isn't all thát important when it comes to making music, but it sure is relaxed to be able to 'see a bit more' of what I am adjusting and changing. This probably is a direct consequence of me not having spend a lot of time yet with my SP-555, so again it's just my impression and opinion so far.
I doubt I will sell my SP-555 anytime soon because I can do tons of useful things with it, but I think it's safe to say that I probably should have bought them in the opposite order hehehehe.
Well, I haven't nearly seen all from the SP-606 yet, so I'll be going to try to hook it up with the P606 software and perhaps take a shot at the battle sample now.