The Ranma OVAs are little side stories to complement the main series. They're short, fun, and have better animation.
Story
Akane has a flashback to her childhood where she was saved from monsters in a forest by a mysterious boy. She hears that monsters have reappeared in a village and she heads off to investigate. She meets the boy who has grown into a man and discovers the nature of the forest.
Ranma chases her and Ryoga shows up too. Hijinks ensue.
Art
The art is actually pretty good. It is better than I remember the original series being. It looks more clean, more consistent, and better animated.
The animals look hilarious with giant eyes and the cutesy proportions.
Sound
The opening and ending themes are great. They're music videos by DoCo, a group made up of the Ranma voice actors (Ranma, Akane, Nabiki, Kasumi, and Shampoo).
Nostalgia alert - Way back in the day of 14.4k bps modems, I went way out of my way to download a motherlode of Ranma music in MP2 form. Yes MP2s, not MP3s. The collection took me weeks to amass. The most recent and rare of the music were the DoCo tracks. I even downloaded the music videos and didn't know where they came from. I just thought it was cool that they used the characters in dramatic montages and there was professionally produced music. Super nostalgic!
Characters
This is Akane's OVA. She gets the spotlight. Ranma and Ryoga are her supporting characters and then there are Shinnosuke and his grandfather.
Akane and Shinnosuke have a little thing going on and Ranma gets jealous. It's a good reversal from the typical.
The Ranma characters are always the strong suit of the series. They're wacky, driven, funny, and occasionally serious.
Enjoyment & Overall
I like the Ranma series overall and this is no exception. It had its funny moments, its dramatic moments, and its fanservice.