Again as the old,adage says, if you have to ask you probabably can't _________...
I am being serious. Think about it. For example, if you are at a level 10 of 10 in terms of possesion if basic technical apparatus and in creative but appropriate expression and Interpreative skills, you should be able to look at just about any score from 8/10 down to 1/10. And almost immediately know how difficult it would be for you and how long it would take to learn which could range for. Sight read at respectable finish to working on it for a few months.
If you look at a score and cannot make a fundamental judgement on its relative and subjective difficulty, then it indicates a big whopping hole in your experience with other literature of similar difficulty and and inability to study scorser for the basic demands it will require of the performer.
Ask yourself. Do you have to ask this question of pieces of music at the same level as works you learned in your first or second year of study of the instrument. Similar deal but on a larger scale for these mammoth works of the standard.
If you will just poke around in it for your own personal study , hey have at it. If you are considering the work for formal study and performance, I would caution you to table it ( it's not a never, just a best if not now...l) and look to eithe ra similar large scale work of considerable less complexity or a similarly complex but much much smaller piece of music.