This is actually the first Cosby/Hope "Road" picture I ever saw. I knew it was the last (after a 10 year break) and (for some reason) was in b&w--probably because Cosby and Hope looked better that way. I also heard it was pretty bad. While it's not great, I sort of enjoyed it.
The plot was REALLY silly and involves the boys in espionage with Joan Collins along for the ride and a (surprisingly) very bad job by Robert Morley as the lead villain. Dorothy Lamour decided to not costar in this one but she does pop up (playing herself) in an amusing cameo and sings one song (Cosby sings too). There's also a really silly and pointless bit when Cosby and Hope are sent to outer space. And the ending is desperate.
Still, it was well-made and Cosby and Hope were a wonderful team--their easy banter is great to watch and they made the worst lines seem funny. Also it's fun to see Collins (who's quite good) so young and full of sex appeal.
So, it's enjoyable way to kill 90 minutes. I'm seen better but I've seen worse too.