Prince of Tennis: A Day on Survival Mountain is one of the few OVAs that contains side stories of the series yet fairly entertaining.
Story: Nothing special; it's just your typical non main plot-related episode with tennis-related activities and some humor thrown in. Though, aside from that, you find it quite entertaining and could keep you watching until the end. The only problem is that there isn't much tennis action, and the longest match could have been 7 minutes or less, but I don't mind that.
Art: One of the strongest points in The Prince of Tennis series. There is a small improvement in the animation, as expected of a special, and there is minimum amount of frames repeated, which is good.
Sound: You might notice that there is a new set of BGM numbers during the OVA. They are similar to the ones played in the original anime series and were nothing exceptional, but it was cool to listen to something new and refreshing.
Character: There isn't much development in this OVA, both in traits and tennis style, though we get to see one new move Echizen did. We got to introduce to a few new characters, but most of them (two are excluded) aren't really special.
Enjoyment: Despite the lack of tennis action, there was humor that could make us giggle and some new tennis tips and training activities that kept me sitting in the chair.
Overall - Prince of Tennis: A Day on Survival Mountain is one of the few OVAs that contains side stories of the series yet reasonably entertaining at the same time. The OVA could be finished in one sitting (of course). In the end, it is a fairly satisfying watch.