ok, at first i would like to recommend not to judge the brand by only a single product out of the usually huge line-up they offer.
i just recently got me the 1gb t10 and before that I used an ifp590... here's what i found out:
# vorbis support from q0 - q10, no volume issues anymore (as there is/was with the ifp series from iriver)
# sound quality in general seems very nice to me, i was satisfied with the ifp already
# you have to recharge your batteries separately, doesn't work via usb cable like it did with the ifp (which featured a li-akku, btw..)
# i really don't like the choice they made about making WMP almost unavoidable - but - almost means that you can get around it and, in fact, you have to do that, if you want to use .ogg or .txt files on your player, since WMP doesn't support these formats at all.
the clear drawbacks of this WMP necessity, you can't use it as an ums device (though there are some versions out there, that are ums - here in germany we get the crappy wmp ones

) and that reduces the usability to the dear old windows os, it doesnt work with linux or mac. for some folks that might disqualify the player completely!
if you use windows, then you can just copy the files to your player, as it shows up as a mtp media device in your explorer, once connected. with the restriction though, that folder creation is impossible. The only way to get folder structures is to copy them from your hd. (you can create folders with wmp, but i hate that crappy piece of ms-softwarejunk, so i don't bother about it.)
final thoughts: it isn't that great a player, i am able to work around the file-transfer issues, others may find this too uncomfortable already. One thing that really impressed me though is the great ogg support this player has, if this is high priority for you, it isn't a bad choice. I like the design and size, too, but that's my very personal point of view, the controls work good for me and there is no stick that can get sluggish after heavy usage, like there was at my older ifp (one of the reasons, i replaced it now).
I hope someone found that usefull, if you have additional questions about the device, just ask and i'll look into it

bye folks!