I don't know about popularity, but most experienced Bitcoin users won't recommend it. I also know that there have been several incidents of Bitcoin loss because of negligence on the part of blockchain.info (now blockchain.com) itself. That doesn't exactly paint a pretty picture regarding its reliability. If you're a newbie and you're reading this, do yourself a favor and switch to Bitcoin Core or Electrum.

I seem to always see a blockchain.info wallet recommendation on threads like this pretty often. Makes me wonder if the posters are really just happy with the service or if there is some shilling going on.