It's interesting to note that while there are many composers who wrote one or two great operas without "warm ups" (e.g. Debussy, Ravel, Bartok, Beethoven, Enescu, Goldschmidt, Gershwin), the great "opera composers" whose works comprise the mainstay of the repertoire all had very humble beginnings in the genre before they found their true voices. Verdi is no exception, and his earliest efforts are pure bel canto creations very much in the mould of Donizetti but without his naive purity - Nabucco is simply clumsy and crude and looks backward to his models, without giving a hint of the genius that was to emerge much later.
I think opera fans who don't listen to other classical music often forget quite how strange the Bel Canto repertoire is in terms of musical history. To name the greatest of the bel cantists' contemporaries, Beethoven, Schubert, Schumann, Mendelssohn, Chopin, and Berlioz were at this time pushing musical boundaries in every way imaginable, expanding the range and scope of musical expression and technique at an unprecedented rate. When compared directly to the incredible invention, sophistication and innovation of these masters, the bel cantists seem hopelessly limited and artistically static, producing score after score of the simplest imaginable musical material, constructed using harmonic clichés, incorporating almost none of the formal innovations of the last half century of music, and all to the most skeletal accompaniments - colour and atmosphere are as nothing compared to the other early romantics mentioned. It's not even that it's old fashioned, because none of the Classical masters would have dreamed of using such simplistic material, and the denial of development or tonal relationships as a way of building and exploring a musical idea is completely anathema to what the Classical composers aimed at.
When well sung, there is however something very potent about Bel Canto opera - a purity and shift of focus where the entire life of the music is in the melodic line - and when it works, it produces a quite magical effect that is unique to it. The opera Norma would be a case in point, but there are several other examples which are of similar quality.
Early in his career Verdi is very clearly aiming at this, but misses entirely, because he can't yet infuse the vocal line with particular character or meaning or even forward direction, and nor does he have the peerless instinct for dramatic situation that miraculously transforms and elevates the far fetched plots of his middle period operas into compelling dramas. The result is that Nabucco, his third opera, is a very long, confused and boring evening, which sets an undeniably dramatic plot (hampered by a weak libretto) to bland music with uninteresting characters.
Daniele Abbado's production updates the action to the 30s/40s/meh. It's still about jews, conflict etc., but the setting is essentially abstract, and the direction essentially lifeless. The set is a big sand pit, with large standing stones which might be buildings or grave stones littered about the place. Occasionally large wire mesh statues are brought on which probably represent important people/ideas/events. Everything is very grey. The back wall is used to project a sky, and sometimes video sequences which depict the exact same action of whatever the crowd are doing on stage - the only purpose of this then is to make it visually slightly more interesting. Additionally, this is the worst case of parking and barking I have seen in a long time: characters barely interact with or even address one another and deliver almost all their lines directly forward. Since everyone does this, the blame must be squarely placed at the feet of the director. At no point is it possible to care about what anyone is singing about. The ROH chorus is swelled to enormous size, but only make an impact during the famous Va pensiero chorus, when they are clustered nervously in a spot light in the middle of the stage.
I said the cast parked and barked and bark they did. The main quality that you could comment on is that everyone was very loud. Bel canto technique was very thin on the ground. The production's Nabucco, Leo Nucci, is just about to turn 71 (younger then than Domingo who will take over this role half way through the run) and though the voice is still very large, firm and in tune, the scooping into every upward moving interval is unbearable and the colour is monochrome. As Ismaele, tenor Andrea Caré also scoops into every high note. One of the principles of bel canto is clean attack, and I am amazed that the ROH, or even the conductor Nicola Luisotti find this to be acceptable. Vitalij Kowaljow is also very loud as Zaccaria, but the bottom of the range disappears, losing colour, texture and volume. This is simple miscasting which again denies the bel canto idea of equally blended registers. Abigaille is the least interesting and rewarding of the nine core Assoluta roles (a vocal ideal which Verdi is all too obviously trying to essay) but Liudmyla Monastyrska does an acceptable job of getting round the coloratura, whilst delivering stentorian decibels in equally powerful high notes and a heretofore unheard chest register (curiously the latter only kicks in quite low and isn't brought up enough to mix with the middle voice). Unfortunately, there's no real assumption of character, and loudness is not the same as intensity of expression. Hers is clearly a major voice, and technically she is very good, but either this is not her role, or there is some way to go towards really using the voice to express emotions and ideas. I don't blame the singers for not really being involved in this production, and none of the rest of the cast buck the trend. Nicola Luisotti does what he can in the pit but depressingly there's no way this lifeless mass of a production is going to be rescued by sprightly tempos or whatever else might enliven Verdi's score.
I can't face seeing this again, even to see Domingo in another ill advised baritone role. Avoid.