The only reason I watched this dross was because I saw the magic name "Orson Welles" in the list of actors appearing (of which more below).
To start on a (the only really!) bright note, the footage of wildlife is very good indeed (although it feels as if this was taken from elsewhere and when the actors are anywhere near real wildlife (apart from the tame ostrich), it consists of dummies/props (Segal and the plastic "crocodile" in the river and Andress swimming quietly past a wallowing herd of hippos at a distance of a few feet in a river (fat chance, she would have been dead in about two minutes, killed by what are actually THE most dangerous animals in the whole of Africa - forget lions and cheetahs!) Apart from the quality of the photography, the NUMBER of animals in each shot is also very impressive; massive herds of hippos, elephants, prides of lions, herd of ostriches etc. I fear this shows how much wildlife has been lost between when the film was made (1969) and now (2020), as nature programmes never seem to show most animals in those numbers these days!
To move on to the human actors; these are largely as are to be expected. I always expect VERY little indeed from George Segal (who must have been one of THE luckiest actors of his time, with everything resting on his photogenic looks), Ursula Andress (eye candy embodied) and Ian Hendry (ALWAYS playing every role in precisely the same way). A disappointment was Harry Andrews. I usually find him a magnetic actor to watch and one who, no matter who the lead star is, seems capable of stealing every scene he appears in. In this case, however, he goes WAY OVER THE TOP and his booming, laughing, lecherous, somewhat sadistic interpretation just did not work for me.
Which brings us to the figure of Welles; absolutely huge/grossly obese at this time (as in "A Ferry to Hong Kong", made shortly before) and obviously just "winging it" in terms of putting any life at all into his part (even though this is admittedly very slim and he does not even appear until about half way through the movie). I felt really sad at seeing him having to take parts in such dross as this, particularly remembering that this was only a few years after two of the (in my view) finest films he ever made: "Chimes at Midnight" (which virtually everyone must agree is a masterpiece) and "The Trial" (which some people (e.g. Charles Higham) certainly do not regard as a masterpiece but which I do in terms of style and cinematic finesse). As Charlton Heston (who starred in another of Welles' undoubted masterpieces, "Touch of Evil") once said in an interview, instead of wasting his enormous talents on dross like this, Welles should have focused on finding a patron or sponsor who admired his work (although being Welles, of course, he would probably never have accepted his position in such a relationship for long in any case!)
A very final thing I found abysmal: the MUSIC/soundtrack is beyond horrendous -cheap muzzak, recorded at ear-splitting levels for much of the film and thrown in at what mostly seemed totally inappropriate moments!
Overall. a REAL turkey and one I am guaranteed never to waste two hours watching again in my life (even with Welles in it)!
