I have a couple of IP autographs from neil and this doesn't come close to them,having said that it doesn't mean it's not real,it could be rushed,but it is just a squiggle and difficult to judge,I wouldn't buy it even if it is real,it's a poor example of his autograph...hope this helps
Not sure about this signature,but he has a signed limited edition biography out with copies on ebay. I got one for 250 (US) but most seem 3-400 dollars for a genuine autograph.
This one came from Markus Brandes autographs. I read somewhere here he can be highly trusted, that's why I started looking on his site and found this NY LP.
Conclusion: likely genuine but very rushed signature?