The best way to review this item it to review the two DVDs separately so that the quality can be judged.
Time-Flight is considered to be a very mediocre story, from the hay-day of the Davison era. I surpose in comparison to the greats from the Pertwee/T. Baker era, this is very true. However, as an eighties effort, Time-Flight is very good.
The useof Concord and the central concept was original for 'Who and the tight script alows Nyssa and Tegan to get an equal share of the action as Peter Davison's Doctor bounces with excitement from scene to scene.
I was never a fan of Doctor 5, however, over the years I have went from thinking him a mediocre Doctor, to an brilliant one. He brought an air of originality to the show.
The extras in Time-Flight are limited but good, with short interviews and behind the scenes 'mess ups'. There's good entertainment here.
Arc of Infinity is in fact a story that I am very fond of and, in fact, have wanted as a release on DVD for some time. Davison is just about at his peak of excellence here. Nyssa gets a great share of the action and Tegan's character is introduced sportingly. The Amsterdam setting is a nice exotic approach for 'Who, much like Paris in 'City of Death'.
Gallifrey is used well (beter than in 'The Five Doctors') to portray the very interesting (and very real) concept of partical antimatter and possible antimatter transfere.
One of my favourite villans makes a return on a much beter form than his previous encounter with the Doctor. Overall, Arc of Infinity shows just how good the Davison era was, with great writing and great acting, along with (mostly) great costume work.
The extras are good with the brilliant documentary (like they always are): Antimater in Amsterdam. It's presented by Sophie Aldred (for some reason!) and provides a good insite into the production and idea in to the serial.
Overall, a good release with two of the best from the Davison era. Give it a chance! Soon, hopefully, the Black Guardian Trilogy will be available as a boxset shwoing the Davison era at it's absolute very, very best. Role on Peter Davison!