Answer from Hernan Giraldo:
Depending on your industry and stage it could be very good. We have had a great experience with this. Main benefit for us has been signaling to other investors. Also, if you are in earlier stage of product development, it is good to have a customer that is patient and gives you a lot of slack while you iterate on product. At later stage and -specially if your customer base is small and very concentrated- it could be a liability to sign up other customers who compete with your customer/investor. You may mitigate this by not publicly talking about it and asking your customer/investor to do the same.
Answer from Derric Gilling:
Just to add depending on how this is structured, I would also be careful about providing “Major Investor” rights to customers/strategics. These typically include things like information rights, pro rata, cosale, etc. It’s much more manageable if you have a certain threshold for these. I am unsure about accepting unaccredited investors though so you may need to check with a lawyer on that one.