i've had it for a little less than a year
previous owner had it for about 2 years (1 year in storage)
the problem mine had is a known problem with the 675's that triumph has yet to fix.
the major problems that people have are
1. crappy rectifier / regulator (easily fixed by splicing in one from a 08 and up R1 or CBR 1000)
2. crappy cam chain tensioner
3. EXBV valve gets jammed once in awhile....but that won't prevent the bike from running if it does. you just get a CEL
other than that....that's about it.....pretty much problems any bike can have.
i'll tell you one thing though....it puts the fattest smile on my face even just looking at her. it's unique, it's fast, it's nimble, and IMHO beats the crap out of the jap I4s since they're all so similar.
no offense to those with GXRS, R6s, and CBRs

i just like to be unique....haha