The boyfriend really, really loves his. He says that it isn't as good as the real thing, but if your boyfriend regular masturbates and doesn't mind a bit of clean-up, the Fleshlight would probably be a neat addition to his life. You might want to try one of the Tenga disposable cups to see if he likes the feeling of placing something over his penis first as those are much cheaper, but for Fleshlights, the boyfriend does love his.
While a regular masturbation sleeve could work, I would keep in mind that most of those sleeves are not built with the same quality/testing in mind as the Fleshlights. In vibrator-world, it'd be like comparing a $10 toy to a $120 toy. They won't really "work" the same, but the $10 is certainly a good starting point to learn if the $120 might be a good buy.
As for recommendations, here are two of our favorite Tenga products:
US Deep Throat: link
And our favorite Fleshlights: