do you mean the upanishads or the vedic corpus as a whole, or specifically the vedas? most people don't read the vedas as a whole, they read the upanishads (1/4th of the traditional division of the vedic literature). the other 3/4s, the rgveda and the brahmanas and even the aranyakas, are mostly tedious formulary for rituals or extremely repetitive/esoteric. even specialists openly call them mind-numbing to read and philosophically uninteresting, in most cases. the brahmanas in particular.
the vedas proper are composed of an original body of ritual formulary, mythological hymns, and extremely occasional metaphysical speculations. these are then broken up into several "collections" (rgveda, yajurveda, samaveda, atharvaveda), with the rgveda being the oldest and atharveda the youngest, and the samaveda and yajurveda being selections/repetitions of the rgveda for the most part. i believe the main theory about the origins of these divisions is that the samaveda and yajurveda are selections specifically for certain grades of priests who only needed them for a specific purpose, and the atharvaveda is a separate compilation of local folk traditions and magical recipes not derived from the original rgveda. they were all collated from orally transmitted hymns and formulary, plus the folk traditions, by a "reform" vedism with a brahman priesthood around 800-500BC.
luckily there are compilations of the most famous, most philosophically interesting bits of the rgvedas. radhakrishnan's sourcebook for indian philosophy is a classic although it's somewhat biased in favor of a monistic interpretation, assuming that vedic philosophy was always internally developing towards monism (which is arguable). but it still has most of the classic rgvedic sections you would be most interested in. wendy doniger's collection is also ok and has a lot of overlap with a newer translation although she is just as biased in the opposite direction, of portraying indian thought as a plurality.
if you want to read anything "in full," be prepared for endless repetition and boredom.
>>15799160
>I would be careful about reading Advaita Vedanta interpretations such as Shankara's as a commentary to the Upanishads, they are extremely reliant on Buddhist philosophy (Shankara is called a "cryptobuddhist" by most Hindus, and most scholars agree). If you want to read the Upanishads, work through them with editions and commentaries that aren't sectarian, or at least read an interpretation that is closer to the original meaning of the Upanishads, rather than Shankara's 8th century AD quasi-buddhism.
pic related
>>15799253
no, the best approach is to read a source anthology like radhakrishnan/doniger so you get the highlights. this can also include interesting bits from the brahmanas and aranyakas, which are few and far between especially for the brahmanas. this is what most people do, along with reading a good history of sanskrit literature so you know what the structure is.