mhbell-
Most coaches have "class problems," that is, problems for a range of model years and models. In the case of the 2000-2008 Winnebago coaches, the frequently-reported class problems are:
1) Leaky windshield (inspection followed by repair if needed)
2) Leaky roof joint (reportedly can be mitigated by regular maintenance)
3) Failure of clearcoat, followed by paint failure, on full-body-painted coaches
Here is a link to a Google search of iRV2 posts with the terms "Winnebago," "windshield" and "leak" in them.
Others have covered, or will cover, the mechanical and systems items particular to these coaches. I note that the "residential," "basement" air-conditioner used in these units have a bunch of happy owners- as long as the A/C is inspected and maintained well.
Don't let these "class" problems keep your friend from buying a 2005 Vectra. They were fairly well-made, according to reports from owners. The 2005 Vectra brochure is
here.