This is a piece of core repertoire which divides listeners sharply.
Personally, I don’t find in the least bit tedious: study with a score shows that there’s far more to the piece than most people imagine: a daring concept flawlessly executed and orchestrated (even if the stuff of nightmares for trombonists; the solo for them is one of the most difficult in the whole orchestral repertoire). Whilst I wouldn’t want to hear it every day, I’m always delighted when it turns up, especially if the conductor actually complies with the composer’s request and starts off at a steady pace and stays there, rather than pushing ever forward, which destroys the effect and emasculates the work’s power (if emasculate is the right word for such a sultrily feminine piece).
Bolero does not work well on record, but if you see it performed, it is a quite different experience. Only when you have it in front of you do you see the extraordinary concentration required by the snare drummer to keep the ostinato going against the continually shifting background of the tune.
That said, I do think that Bolero can be the most tedious piece ever. When it’s not played right that is. All too often it’s played, rather nicely, as a stock orchestral showpiece. Complete with “Oh no, not this again” 1812-style boredom from the orchestra.
Occasionally, just occasionally, it gets played dead straight, in strict tempo (vital to any sense of menace being sustained) and builds inexorably from inaudible to a mechanistic yet brutal sonic assault – though this can only ever be experienced in the concert hall. Then it’s anything but tedious.