As a whole, Bleach is an excellent anime, with excellent characters, good music, a moving plot, and thus you have a constant desire to find out what happens in the next episode. Everything, from the plot to the characters to the battles gets developed within an arc, which is about 25-30 episodes, give or take. That's where the biggest inherent problem lies with The Sealed Sword Frenzy. What has to be done in this 25-minute OVA is start and develop a plot, introduce and develop a new villain, and have Ichigo fight and defeat said villain, something that usually takes an entire arc inthe series.
As a result, the plot has to move quickly in order to get everything accomplished in 25 minutes, and as a result, plot and character development are extremely weak. It also doesn't help that the main villain gets next to no dialogue, but at least his motives are explained.
One can feel that the OVA was made on a strict budget, since the animation quality is at least 2 steps behind the anime series, and the battles extremely watered down, especially the result of Ichigo's first encounter with the villain. The only place where I felt the animators spent time with the art was in executing the villain's special attack in the final battle. And then the plot problem comes back. The problem of having to devote time to explain who the villain is and what his motive is, which makes the battles extremely short and disengaging. And since there is no plot development, the struggle between the two fighting sides isn't gritty and can barely be felt at all.
What exactly is the purpose of this OVA? It wasn't made to be a masterpiece and just uses the Bleach name to promote itself as a reason to watch it. I wouldn't say it's a complete waste of time, but if you choose to skip it, you're not missing much.