I see where you guys are all coming from and I agree, the plot lines, characters and settings are
somewhat randomly compiled. But still, when I was younger I loved "Birthright", because we got to see the TNG characters walk the DS9 set.
Plus, I always liked Bashir, so I never really perceived him as a substitute. All in all, I don't think the episodes are all that bad. Granted, it doesn't really work as a two-parter, but the single plot threads are rather interesting when looked at them individually.