I got the first couple of dozen of these, and then cancelled my subscription simply because I never got round to listening to them! A few years later, I still have a few of that batch I've never heard!
I recall Land of the Dead being a bit lame. It falls into some very lazy dialogue: "Look Doctor! There's a giant monster with two heads and green skin climbing down that ladder to your left!" kind of stuff.
The best ones are the Colin Baker ones. Bonnie Langford is a revelation as Mel, and the new character of Evelyn is worth a listen, too. She's a retired academic, and completely breaks the "Dr Who Girl" expectations. Maggie Stables gives a very good performance.
The stories with Ace tend to drag a bit, as Ace has now dated and got very old-hat. After all the books, there's very litle new that she can do.
Turlough has only appeared in one or two of the plays, I think, which usually leaves the fifth Doctor with Nyssa. A bit limiting. Peri's occasional appearances are nice to listen out for though.
My top tip: The Spectre of Lanyon Moor (sixth Doc, Brig, Evelyn). Great fun.
chuff.x.