Yeah, I kinda phoned it on in regards to Apblanc. But to be honest, his whole situation confuses me. I really, really, (and I can't stress this enough) REALLY hate time travel stories. I confess that my personal bias in that regard made it nearly impossible to focus on the story in Forlorn.
As far as Strahd goes, he has indeed overcome many of his weaknesses as a vampire. Garlic, mirrors, and holy symbols do not cause him any undue distress. (Although I remain a little confused about mirrors. I assumed this entry only meant that he does not recoil from a mirror, not that he actually casts a reflection.) He can still gain partial actions in sunlight, and doesn't take damage for ten full rounds. As the only landowner in Barovia, he can enter into anyone's home. This last one isn't so much an example of him defeating a vampiric weakness as circumventing it. It's entirely possible that if he were to leave Barovia and go somewhere he was NOT the liege lord, he would still need an invite to go somewhere.
There are many more weaknesses he has not overcome, though. Running water is still a problem for him, and there are some particularly wild rivers in Barovia. A wilderness encounter at one of Barovia's mighty waterfalls could be a suitably epic way to temporarily 'kill' Strahd if any DM was so inclined to orchestrate one. Wooden stakes are again a problem, and much worse than the water. It's rather simple for a vampire hunter to bring or even to manufacture a wooden shiv; they have a significantly harder time diverting a river through Castle Ravenloft!
And of course, although there is no mechanical disadvantage associated with either of them, Strahd has two additional weaknesses from his vampiric state: he hungers for blood, and is compelled to sleep during the day. Neither has a numeric penalty for failing to comply, but it still seems reasonable that they might be compulsions Strahd would like to rid himself of if he had the opportunity.
This doesn't even take into account the weaknesses that come along with being an undead. He's still vulnerable to cure spells, holy water, and a host of spells both arcane and divine that are designed to harm, influence, or confusticate the undead. If you are using the standard version of the turn undead ability, a cleric would need to be 25th level to even have a shot at turning Strahd, so he's got little to fear from that, but every DM I know uses the damaging turn undead variant from Complete Divine, which he is still quite vulnerable to. In point of fact, a 20th level cleric (the lowest level PC that Strahd could tangle with where the party would have a reasonable chance of defeating him) under that system does an average of twenty-six points of damage, assuming Strahd makes his Will save to halve the damage, which he does on a roll of 7. If he fails, he takes an average of sixty-one points of damage, possibly much higher! All the DMs I know utilize this system, so it seems reasonable that Strahd would be seeking a way to up his turn resistance as well. (Which deducts from the damage, if you aren't familiar with that variant.)
In any event, I hope that helps!

