Personally, I like it... but there're so few nowadays. Back then I was intriguied to watch MJ in Space Jam, Dennis Rodman in a Van Damme movie (forgot the title), Whitney Houston in The Bodyguard, etc.
I actually do, particularly singers/musicians who have had successful careers beforehand. I think it's quite a feat to have a well-established public profile and then act in a film where you have to be convincing as someone else. Many fail, but the ones who succeed (such as Whitney as you mentioned, Dolly Parton in 9 to 5, Mark Wahlberg in Boogie Nights, Bjork in Dancer in the Dark, Michael Jackson in The Wiz, Lady Gaga in A Star Is Born etc.) impress me, because I do love an all-rounder.
But I particularly like the more wacky gimmicky roles... like Kareem Abdul Jabbar in a Bruce Lee movie or, like I mentioned, Dennis Rodman. Mike Tyson has had some appearances in movies like Hangover and Ip Man. They add the excitement, not just a basketballer plays as basketballer or a singer as a singer. Those were fine too but not as exciting.
Unless I dont like the famous person then, I dont feel one way or another about it. If they do good then good on them, if they suck then I laugh at them. Pro wrestlers seem to take to the silver screen the best though lol.