I just started this as a hobby. I like the controller a lot. But serato intro is just not enough to take advantage of the controller so you might want to look at the paid version.
TBH, i'd rather stick to rekordbox after have both trials. Rekordbox 4.1.0 was just launched, btw (still didn't tried it though).
back to ddj-sb2, for what it is, I can't fault it. feels good, it sticks to where you put it despite being light, looks good, the jog wheels respond well enough for a starter like me and both softwares (and mixxx) seem to respond well enough (but rekordbox somehow seems to have a slight advantage wrt to lag if you want some nit-picking)
Effects usage are not a burden unless you don't have the cpu power (like analyzing in the background your whole library and hogging that USB bus too :p )
Lots of features like the VU LEDs are worth it too. The tempo sliders are short but in the software you can change the range to make up for it so no issues either.
The pads are very responsive too and the layout for both serato and rekordbox are easy to access and understand and the shift options gives access to even more.
ofc, we always want more but for the price range I think I made the right choice on this one.
But ofc, take this with a grain of salt as i'm very new to this and no intention to make it more than a hobby.