Not one of the more popular Davison tales, this one. Having re-watched it recently, though, I'm not quite sure why it gets panned as much as it does. Certainly it brings back Omega without adding much to his character or pathos, and it's part of the much derided old-monster-fest-instead-of-fresh-ideas phase of the series but it is, nonetheless, quite a solid story.
Admittedly, the bringing back back to gallifrey in criminal mode only to become a hero bit feels at first like an inferior retread of the Deadly Assassin especially when the game of who's-the-traitor starts (for Hedin read Goth), but there is a different spin on it here- and the detective work by Tegan in Amsterdam keeps things fresh and gives her character a chance to shine. Davison and Nyssa make a good opening team and Nyssa's battles (with tongue and gun!) give her some strong stuff also. The unravelling of the aborted termination of the Doctor makes for an intrgiuing third episode and the Doctor-Omega finale is solid. Yes, the chase basically shows off the location, but so does some stuff in City of Death and that doesn't get hauled over the coals for it.
It the story lacks anything it's really directorial flair- Something often happening in this 20th season alas. Ron Jones does a competent job, but he had yet to really find his feet- his work on Frontios and Vengeance on Varos would outstrip this by miles. Davison's acting often lends a flair and pace that the direction simply lacks, as if compensating- though having said that the darkly-lit Omega scenes in parts one and two look very impressive.
Was bringing Omega back worth it? maybe, maybe not- Rassilon might have been a better story subject as we know a lot less about him bar what the New Adventures and Big Finish audios have filled in, and good as they often are, I don't know whether non-TV stuff can really be canonical as the TV series reserves a perfect right to disregard it as it did with The Ancestor Cells' Gallifrey demise. (OK, so I know as far as they knew at he time there never would another TV series, but now there is!We could say canonical till proven otherwise?) Nonetheless they could have picked a worst subject. As part of season 20 this pales beside Snakedance, or Enlightnment, or Mawdryn Undead, but compared with Terminus, Kings Demons, the preceding Time Flight etc...it's really not so bad. Yes, a steal from ASSASSIN in places, but a lot of WHO plots are recycled- and this does enough of its own stuff to stay fresh. An entertaining and underrated story.