A good performance? Absolutely. But I don't think it comes close to Images and Words or Awake.
Agreed. In fact, I think of all the guys, James's performance, while excellent, is less boundary-pushing than usual.
Let's give him some credit. On this album he actually sings his highest note on any DT album, including "the" F#.
This is truth. BMUBMD contains his only studio A5 to date, although he's hit that note live an assload of times by now. There's not much high-register stuff otherwise, but that particular segment is mind-blowing if you actually pay attention and realize he's screaming (ridiculously high) notes rather than random shrieks.
As for the overall performance, it's definitely one of his best and most consistent, but I wouldn't say THE best. I'd say SDOIT has the best tone, strength and clarity of his performances, and IMO the best quality of singing in general. I am massively biased towards that album, it is my all-time favourite album after all, but even just singling out the vocals, the baritone vocals on Disappear (I actually like low vocals better than highs, although James can do both excellently, which is even better) and the incredibly multidimensional vocal work on the title track constitute the best voice work I've ever heard. His voice just oozes with emotion through the whole album.
The runners-up are IAW, which has his best highs, and Awake and Octavarium, which I think are his best displays of overall range. ADTOE is probably after these albums in the ranks.
Also, agreed on ITPOE's awesomeness. The vocals throughout Part 1, as well as Heretic and the finale, are phenomenal. Forsaken and TMOLS have great vocals too, though the heavier songs on the album don't exactly show his voice at its best.