I've seen a few threads on the discussion between bottling into PET vs glass. I'm only a few (kit) brews under my belt but my experiences thus far have found there to be a very clear winner to this question: Glass is best.
I've got a full complement (48 bottles) of both Coopers PET bottles (brown) and St Peters glass bottles (green). In all brews to date I've made a few observations:
1) Beer appears to condition quicker (and achieves a nicer, more mellow taste) in half the time in the glass bottle (the PET gets there but much slower)
2) The PET does not carbonate as well
3) PET are harder to keep clean (I'd avoid a bottle brush with them) and harder to clean (easier to knock them over or find them floating when fitting them with a cleaning solution)
4) Glass work better with the bottles rinsers (due to the narrow neck compared to the PET)
5) And for similar reasons, the glass pours better too
6) Glass 'feels right' where as serving from plastic does not
7) The 'ridges' on the base of the PET bottle make it harder to pour without disturbing the yeast (due to the turbulence they promote when pouring)
I'm sure some will disagree but wanted to get my opinion out there. I'd planned to buy a few more cases of the Coopers bottles (lighter and won't smash as well as being very good value) but given point one (and two) above, in particular, it's just not something worth considering. The others points are interesting but not absolutely essential, the first two however are - The beer has to taste right. In all of my brews after 6 - 8 weeks conditioning I've poured both a beer stored in PET and a beer stored in glass and blind taste tested (blind folded and had them passed to me backwards and forwards a few times not knowing which was which in order to check, and double check, which was best). Every time the glass one tastes better. I've just done the same with my most recent brew and whilst the glass bottled beer could still do with a little longer to mellow further the PET was completely undrinkable! I was going to bin it, but, well... You understand!

So: my summary... Glass beats PET hands down. I won't bin the PET for now - at least until I'm pushed for space - but I see no reason to bottle in them again otherwise.
And, your experience?