Yeah, technically there isn't a sequencer, but this isn't too bad in my opinion. A way that I plan to work around this is to use each pad in a bank as a different track. This works if you're playing a(n) instrument(s) into the imput. You record each part on one pad and then essentially have a 12 track sequencer (I don't understand why there isn't 16 voice polyphony). Then you just trigger all the tracks at the same time. You just have to make sure they all have the same tempo

. Another cool way to do "sequencing" that requires more live performance is to have a different loop on maybe 4 pads (or more if you want) that would each be the backing track for a different section of a single song. Then on the other pads you could have different types of hits and riffs to make things interesting (something I like to do is have a mini "drum kit" on 4 pads consisting of a kick, snare and an open and closed hi-hat. This alows you to mix up the drum beat in real time. You could then also have some riffs or vocal samples to throw into the mix. Then on top of all of this you could plug in a keyboard, guitar, or mic (or anything else you want) and solo/sing over the hold song. It's a pretty versatile piece of equipment if you think creatively.
I don't mind a lot of the SP-555's flaws, cause I don't plan on looping in front of a live audience, but I really wish there was more than 15 seconds for loop capture. I hope Roland fixes this if possible.
Sorry, long post
Edit: And of course you can use the pattern sequencer too if you do things a certain way.