I SO don't want to hurt your feelings and am far from being an expert but while the puppy IS adorable - he does look mixed.  Only for YOUR peace of mind am I posting - but if you fell in love - then go for it - if you're having doubts - there's lots of puppies out there.  
 
IF I were you - I'd look at this with an open mind - many 'not so good' breeders lie (about the parents etc).... But - with a 
good breeder - you shouldn't have doubts  
you just have to go with your heart on this one 
  
and Diego - that was horrible what someone said about that pretty girl.  I can't believe anyone would say that about ANY puppy !