As a gigging semi-pro bassist in a covers band, I needed something to help give a reasonable impersonation of the Muse bass sound. However, Akai don't make the "Deep Impact" bass synth used by Chris Wolstenhome any more. You c an pick them up second hand on ebay providing you don't mind another mortgage to get one (think north of £600). This little Boss unit does a fair job in terms of the sounds you can get and the tracking. The price is far more sensible when you only need it for a couple of numbers a night.
On the downside, there are no pre-sets and if you need to change sounds on it during the gig it's fiddly. Just a point about the sounds you might think about setting and using on it. Like most guitar effects pedals, what sounds great on your own in rehearsal at home can sound awful (or just not "cut through") in a full band situation. By the same token, less inspiring sounds you set while playing alone can be a whole lot better when mixed with the other guitars. Plenty of experimentation is the key I guess...
The service was amazing and the build quality, clarity of instructions and intuitive controls are also amazing. Where this product fails is the appalling tracking. The pedal is great to play around with but for practical applications (i.e actually using it to create an audible sound) the tracking makes it impossible. Eighth note and sixteenth note patterns, even playing with a pick and muting the bass strings to be as precise as possible, gives a sound comparable to that of randomly hitting keys on an actual synth. The tracking is so bad that even creating a completely artificial bass line using reason software that was mastered and 100% consistent, recorded onto a boss loop station and then played through the SY-5 still came out almost unrecognisable due to tracking issues. The pedal is slightly more manageable with an expression pedal, but even boss' own expression pedals lack the range to fully sweep the decay knob meaning you only get about 50% of the potential use of this when you use the expression pedal. I found that adding a compression pedal pre SYB-5 also helps to manage the tracking but compression is DEFINITELY needed to manage the signal coming out of the pedal because of the extreme volume levels the pedal produces, which means you would need to invest in two compression pedals. In is favour it is a great edition to a good distortion pedal (pre and post (the distortion helps to mask the incomprehensible random out of key notes that the poor tracking produces)) as it gives the distortion an extra dimension. To sum up, if you want a well made synth pedal the Digitech is much more usable and the extra money you save can be invested in impressing the groupies with your drink buying skills at your next gig. You could also put some over time in at work or save a bit more or simply sponge from your parents and buy the Mark Bass super synth. Its expensive but the price comes with the fact that it is almost flawless and works perfectly.
It's very well made like all Boss pedals, and can make some cool synthy sounds. The problem for me is the tracking. You can't play 16th notes because the pedal won't keep up and the synth tones drop out. You have to dig in pretty hard to get it to trigger reliably - I play quite soft fingerstyle so you might be better off playing with a pick. On the other hand you have to make sure that you mute the strings well, play because it can be triggered by open, ringing strings or even on harmonics. Once it made a horrible electronic screech like a Dalek in pain just as my band was about to start a song - no idea at all why!
Overall I would say that lots of experimentation is in order to figure out what it does and when it does it.
This pedal is rather awesome, in most ways, simply, i cant be bothered to write a proper review, but i just want to include a warning. Well, two actually. First off, it's VERY LOUD. Much louder than the natural output of an electric guitar. Secondly, it doesn't come with a power cable, and batteries are not a replaceable thing. I've managed to make it work using a 7.5v casio keyboard power adaptor, rather than the recommended 9v Boss adaptor, but even so...
Also, by way of expression pedals, a piano-keyboard sustain pedal does the job just nicely ;)