Are NS&I OK?

A question about : Are NS&I OK?

I'm considering opening an NS&I cash (Direct) ISA. Are they any good?

Does their website work properly? What is the online experience most similar to:
- Post Office: rubbish. Can't transfer out, always some error, need to write letters, etc.
- Sainbury's: limited functionality and sometimes a bit slow sending money out but otherwise perfectly good
- Tesco, Nationwide: sometimes down, but otherwise good
- Lloyds and the like: good

I am particularly worried due to their link (ancient history) with Post Office. I find most government sites run well but now always cautious after terrible experiences with some (Post Office, Clydesdale, etc.) that do not invest in site/technology or customer service.

I just plan to use the ISA product, depositing once a year, no withdrawals but need to know if I needed to I could do it online without shenanigans.

Best answers:

• 14 questions in two days?
• The Direct ISA is managed online with NS&I. Transfers in and out can be done online. May need to use a Debit card to set up the account though.
  There is some postal correspondence when you open the account and paper statements (but you can turn these off).
  Generally they are very good. Much better than some of the banks.