The story follows up the end of the tv season so you should have watched the season beforehand.
This time you could say Daigo is the protagonist. You know, the stereotypical best friend of the protagonist who will never get a girl. And exactly that is the OVA all about. Daigo aproaches nearly every girl (and even their mothers q;, well, more or less accidently). It's quite funny but you should not expect any development of course. If you liked the tv series you might as well watch it there are enough occasions to laugh and maybe even a happy end for Daigo.
For Animation and Sound it's the same as the series, well I liked it in the first place so not much to say about.