Trails in the Sky is the best story-based JRPG on the PSP (really no contest considering the feeble story-based rpgs on the system, but I digress). With the uncertainty over whether XSEED can bring the other two installments over to us poor non-Japanese understanding masses, this OVA could potentially be the only way for us to experience the continuation of the story from the cliffhanger of the first game as my understanding is that it's based on a chunk of the second game (and, obviously from the trailer, the ending of the first).
So, I'm actually a bit torn. The last thing I want to do is ruin the second game by watching the story (it's a story-based JRPG after all). Yet, without any certainty that the second game is coming, if XSEED doesn't proclaim that it's a go by the time this OVA is out, I'm going to be hard pressed to resist the temptation of watching.