You can take a look at my quotes.module.  It can import several
quotes through a single node submission form.  Although the concept
is a bit different from what you are doing, it does have to
individually validate and submit each quote.  You might be able to
get some hints from it...or give me some hints if you see problems
with my code!  ;-)

The problem with your importing code is exactly what I was pointing out. Suppose I attach a required taxonomy to the "quotes" content type. You don't set it. You don't validate it. Still the node is created.
Or if I use hook_form_alter() to add a "#required" to the title textfield so it must be non-empty... you'll happily save the node without the title set.

You also bail out creating quotes from the first error you encounter while I would like to import the next rows too.

I may have misread the code.

Now for your specific case, this may be ok, but for a generic node_import it is not.

Robrecht