The Three Doctors
The Three Doctors is a load of old tat, according to conventional wisdom. However some people say the same about The Five Doctors and the entire Pertwee era. Personally I think it's a genuinely strong story. It has great characters and some of Doctor Who's best comedy... in all seriousness, I laughed more at The Three Doctors than I did at City of Death. Gellguards aside, what's not to like? Admittedly it looks silly, but we're Doctor Who fans. We should be able to see past that.
The reason to watch episodes 1-3 is the comedy between the regulars, who are fantastic. Dr Tyler and Sam Whatsit don't add much (although I loved Sam's last line at the end of episode four), but they don't matter. The Three Doctors knows who its stars are and cuts back everything else to maximise their screen time.
Troughton doesn't exactly underplay his role, but that wasn't his specialty in the 1960s either. The always-impressive Nicholas Courtney makes good lines look fantastic... this is famously the Brigadier's "I'm pretty sure that's Cromer" story, but somehow he actually avoids looking like an idiot. He's wrong, but for character-based reasons rather than plain stupidity. Nick Courtney gives us a man who's always found the Doctor trying but is now discovering that Troughton could give even Pertwee lessons in stretching your patience. The Doctors work together wonderfully, of course. Troughton and Pertwee were both masters of comic acting, while there's a freshness to their scenes since their Doctors had never previously had to operate in anything like this kind of relationship.
William Hartnell is okay. Sadly the poor man's condition meant that he had to read his lines off a cue card and only appear on a monitor, which simplified the plot but means that his Doctor has none of the force and power of which Hartnell was perfectly capable. He also looks strange on the TARDIS scanner. He's orange. He gets a good line or two, but as a performance it's pretty sad compared to his usual standards.
Benton makes a good companion, incidentally. Like Jo Grant, the character has an endearing "I may not be very bright but I'm doing my best" earnestness about him. I'm also glad that Richard Franklin took time off to direct a play, because Captain Yates was the one UNIT regular who hadn't met Troughton and he might have diluted the byplay.
The story's other big plus is Omega, who's a wonderful creation. I'm tempted to call him Doctor Who's finest villain, a Shakespearian figure of tragedy and complexity. The Master and often even Davros are simply evil. They appear in better stories than poor Omega, but they're rent-a-baddies who can be inserted into a random script and left to get on with their latest Plan For World Domination. However I wasn't kidding when I called Omega Shakespearian. He's like Prospero's deranged twin, if he'd been stranded on his island for ten million years. We feel his tragedy. He earns our sympathy even when we realise that he's become a ranting monster intent on destroying everything.
Omega's story is the most iconic in Doctor Who's mythology, but he's not just an eye-catching high concept. The character has depth and complexity too. Stephen Thorne manages to fit a surprising amount of naturalism into a performance that's necessarily full of declamation, theatricality and over-the-top ranting. Compare with Season Sixteen's godawful Pirate Captain for instance. You never doubt the power, grandeur and insanity of the man, but at the same time he feels real. His childishness extends beyond those temper tantrums. When he's thwarted, he almost cries! I love the way Stephen Thorne puts a crack in his voice at that point. I now want to rewatch Arc of Infinity, especially Davison's performance as Omega in its final episode, and those aren't words you'll hear too often. He even has a personification of the dark side of his mind! On top of that part four's revelation is a great SF twist, giving Omega yet another black irony.
The obvious comparison with The Three Doctors is The Wizard of Oz (but this time there really isn't a man behind the curtain, ho ho), but I'm going to suggest The Tempest. Both stories are about an exiled king-in-waiting who becomes a wizard and creates a magical storm to summon his usurpers to his island. Both are full of magic, or at least the Doctor Who technobabble equivalent. Both are more interested in character and theatricality than plot.
The Gallifrey scenes are okay. In episode one they're ghastly, pissing away any grandeur the story might have had with horrible technobabbly dialogue and po-faced uncomprehending delivery, but things improve in later episodes when we can see how much trouble they're in. Incidentally two of the three actors credited here as Time Lords had also played such parts previously. Clyde Pollitt was in The War Games and Graham Leaman was in Colony in Space. The better-known example of The Deadly Assassin's Chancellor Goth also being in The War Games was just a coincidence, Bernard Horsfall being one of David Maloney's favourite actors. All four of his Doctor Who roles were in Maloney-directed stories! However it seems clear that here Lennie Mayne was deliberately casting former Time Lords.
We see some minor traditions of multi-Doctor stories.
1 - Bessie will get teleported along with the 3rd Doctor.
2 - One of the Doctors will get trapped on a TV screen, thus freeing up story space for the others.
3 - It's always the latest incarnation who does the actual investigation. He's still the hero. His predecessors are just colourful guest stars.
I adore the Gellguards. The weird multicoloured blob is freaky enough to look effective, but the Gellguards are hilarious. You'd think you were watching a Graham Williams story. For a man who so obviously loves theatricality and impressive costumes, Omega has a mysterious tendency to make goofy monsters. Scarily the Ergon was an improvement! Admittedly the Gellguards look pretty in close-up, with the colours on that bubbly oil slick surface, but in motion... oh my. It's the way they bounce as they wobble forwards.
However on the plus side, the singularity technobabble makes sense! The laws of physics really do go peculiar at the heart of a black hole, so it's not unreasonable for Omega to be exploiting those peculiar properties... especially since those are the exact forces he'd harnessed aeons ago to create the Time Lords.
I also love part one's cliffhanger. The Doctors know what they have to do as soon as Hartnell tells them about the bridge, but they mess around with comedy coin-tossing and we think it's just a bit of fun... until Pertwee walks outside and LETS THE MONSTER EAT HIM.
The Doctor's exile being rescinded is a nice touch, but it would have been more meaningful if by then he hadn't had full control over the TARDIS anyway. Season Seven's production team played fair with the Doctor's exile, but by the time of The Time Monster the TARDIS was seemingly as free as a bird. Had they still been taking that seriously, the production team might have realised that they missed an opportunity in this story. Troughton presumably didn't have Pertwee's memory blocks. They could have had comedy with one Doctor being reliant on the other to fly his own TARDIS, or possibly even stealing back his knowledge of temporal physics through telepathic contact with his previous self.
Like The Five Doctors, this story is underrated. It looks and feels like glittery nonsense, but it has Omega, a great cast and some of Doctor Who's best comedy. Admittedly the story doesn't move quickly, but that was the format under Terrance Dicks and Barry Letts. Even the good Pertwee-era stories can be tortoise-like. Seriously, I was impressed.