Is it? I haven't noticed that. I've got Vista Home Premium 32bit and I have noticed nothing to suggest any serious flaws with Vista. I have heard of bugs such as excessively long data transfer times, but on my copy, I shoveled 40 gigs of music across in less than twenty minutes so I don't know about that one at all.
My copy is OEM and I'vve really had no problems at all. It's ram hungry but that IMHO is a good thing - ram is faster than HDD. What is true is that there are major redesigns in Vista that have meant third party hard/software suppliers haven't caught up - woe betide anyone who has a creative soundcard for example and I understand Itunes doesn't work with it either, but I recall this was the same when XP came along, so you can hold off for manufacturers to get their act together with drivers and software I suppose.
One thing - anyone who's spent a day setting up a fresh install of XP will welcome the driver bank in Vista - install it, it detects your hardware and installs the majority of drivers before you've had time for a cup of tea. Off you go.
You will get all the MS detractors on here telling you what a waste of time it is, but I've run the OEM version Since February and I think it works just fine.