I picked The Maltese Penguin under the impression that it came roughly here in sequence, though it looks like I was incorrect; anyway, it features the Sixth Doctor and his penguin-shaped companion Frobisher from the comic strips, in a spoof of The Maltese Falcon which won't mean a lot unless you are a) a fan of the original film and/or b) remember the original Six/Frobisher comic strips with some affection. I fall into neither category and it left me rather cold.
The Holy Terror also has Six and Frobisher in a peculiar mock-Roman Empire world with bizarre rituals of imperial succession. I started out rather liking this setting (more grist to the mill of those researching the reception of the classics in sf) but ended up not liking it much after all; the off-hand treatment of violence and torture reminded me of the worst of the Sixth Doctor TV stories (I may be thinking of Vengeance on Varos). Frobisher is basically a one-joke character, and it just wasn't very funny.
Last of the Titans is a nice little piece, with the Seventh Doctor (sounding very Scottish) materialising on an all-but-abandoned spaceship and gradually working out what the two other creatures on board are really up to. The solution is a bit implausible but everyone does it with great conviction.
Now for the good one. Storm Warning is the best DW audio I have heard to date. I had been warned by Alex Wilcock, and of course he was right. Funky new arrangement of the signature tune, and the return of the Eighth Doctor, in a brilliant soundscape evoking the disastrous maiden voyage of the R101. Gareth Roberts (Blake from Blake's Seven) is fantastic as the sinister Air Minister, Lord Tamworth, India Fisher is great as new companion Charley Pollard, and Paul McGann is simply superb. Also I see that this appears to have been the first DW written by Alan Barnes, who also wrote the two Gallifrey episodes I most enjoyed. I believe the next three in sequence are all Eight stories, and very much look forward to them.