When I consider whether a show is worth watching there are three main factors I take into consideration: quality, entertainment factor, and the overall message.
Since I have only seen the first three arcs (Agent of the Shinigami, Soul Society: Sneak Entry and Soul Society: Rescue) this post will only cover those.
Bleach began as an adaptation of the popular Shonen Jump manga beginning in 2004, animated by Studio Pierrot of Naruto fame. Due to its popularity and similarity to other popular titles, Bleach became known as one of the "Big 3" alongside Naruto and One Piece. Compared to the other two, Bleach is a more modern Japanese setting which, for Westerners, can make it more difficult to get into due to the very noticeable cultural differences displayed.
Quality
Unlike Naruto, Bleach isn't especially visually impressive. This is very likely due to Pierrot having to allocate a budget to both Naruto and Bleach. Since Naruto was more popular it would have received a larger budget allocation. The character designs are distinct and are all quite cool, but the animation is minimal, even during important fights. This is a problem because the fights are supposed to be the most exciting part of the show and a lot of fights have importance to characters or the plot. It is regrettable that the fights are so dull. In a stunning contrast to this, the audio quality is impressive. While I am not a fan of the style of music used in the soundtrack, it is used well and is not shabby at all. There are MIDI noises here and there which is quite charming. The voice talent hired for the extensive cast is very good. Big names like Hayami Show, Park Romi, Miki Shinichiro, Sugiyama Noriaki and many others. Bleach would be a good show if sound was all that mattered.
The plot of Bleach starts of as a simple normal-guy-gets-abnormal-powers shtick and stays that way for 15ish episodes. Early on there are some good encounters with hollows (the grunt-level enemies), especially when involving character backstory, such as for Orihime and Ichigo. However, in these introductions Ichigo's friends Chad and Orihime get magic powers for some completely unexplained reason. This is a strange decision and the assumption is that it will be explained later, but it's lazy writing in an attempt to make Chad and Orihime not useless. Of the friends, Ishida is the most compelling due to his different powers and backstory. The story picks up once the Soul Society, a Soul Reaper organisation, enters the real world to take back Rukia for punishment for breaking the rules. There is a short fight to demonstrate that Soul Reapers are the real deal compared to hollows. Once the two Soul Society arcs begin things become both more and less interesting. In the scheme of things, Soul Society arc is quite interesting. There is some politicking between high ranking SS members, three good fights (Ichigo vs Renji, Ishida vs Kurotsuchi, Ichigo vs Byakuya) and some cool power mechanics that are vaguely explained. On paper this sounds good but the execution is weak. It's comparable to the Star Wars prequels in terms of good ideas being squandered by weak front-level talent. This is the responsibility of the director and they didn't do a good job.
The characters in Bleach can usually be defined by one or two core characteristics and quirks. Some are notably interesting, such as Aizen, Ichimaru and Byakuya. These characters get a fair amount of screentime, but there is a much greater problem which is a big red mark against Bleach's name in terms of characters. There are far too many characters in the show. I've not had so much difficulty keeping track of characters since the equally packed Shirobako. This isn't an issue on my part since I coped very well with the large character count of Legend of the Galactic Heroes, Naruto and Haikyuu. Having so many characters doing things all the time is frustrating because although they all have distinguishing features, it dilutes the entire arc and dampens the stakes. It's hard to care about the main plot as much as you would like to when 16 or so characters keep getting equal or more screentime. This was Kubo's fault for trying to stuff so much into little time. There's also the issue of Ichigo getting far too powerful with so little training. Obviously, this was going to happen since battle shounen are always unbelievable in some fashion, but Ichigo was immediately on captain level strength after a brief training period. This doesn't mean he's the strongest, but he's stronger than the majority of characters for no reason other than he's Ichigo.
Entertainment Factor
Due to the excessively high quantity of characters and sparse animation, Bleach can be difficult to enjoy. If you have not seen a battle shounen before this might be a fun ride. For anyone that has seen battle shounen Bleach will be more of the same. There are fun characters and the plot is interesting enough, but there's not a whole lot of substance to enjoy. The dampened stakes from the very large cast means there is less tension and emotional investment in what is happening.
I find myself comparing Bleach a lot to Naruto. Early Naruto spent the time to introduce the power system, the characters and the plot. Bleach spent almost no time introducing the power system, a decent amount of time introducing the characters at the beginning and did a horrible job of introducing them later and introduced the plot in a hurriedly way to try and speed up the show. Whatever way you look at it, Naruto was a more fun show. I've noticed an important factor in this is the animation of the fights. This comes down to a fundamental creative decision: the power system. Naruto's power system has a lot of hand-to-hand and physical combat. Movement and mobility is a requirement to not lose most of the time. Compare that to Bleach which, as we have seen, is hitting swords against other swords. That's not interesting or entertaining to watch.
Bleach had the potential to be fun, but potential doesn't mean much when something isn't done.
Overall Message
Contrary to what many fans may say, the message of Bleach early on is not about hard work winning out. It is the exact opposite. "Hope you win the genetic lottery and start off strong because otherwise you'll be on the sidelines." Ichigo never has to work all that hard compared to anyone else like Naruto did. He starts off quite strong and progresses faster than anyone else. A lot of his power progression happened off screen. We had two brief training sessions, but they were power boosts rather than a progression of power. We saw a few steps along the way, but it was still a jump.
Byakuya's character has an interesting character dilemma, being that he has to choose between upholding the rules to keep society stable, or to break the rules to save someone he cares about. The anime doesn't touch on this dilemma with much depth so it's an idea that is thrown out rather than a message of the show.
Other than those messages, there is nothing else to Bleach. There isn't any philosophical message, there aren't any well explored themes and there is nothing of substance.
Since the message of Bleach is something that you may hear from the mouth of Richard Spencer, the quality is mediocre to average and the entertainment factor is squandered by some serious issues the show has, Bleach ends up as a show with very few reasons to watch. You would do much better to watch Naruto for a nostalgic battle shounen or Hunter x Hunter for the best battle shounen and a great show.
Should you really watch Bleach's first three arcs?
No. No you should not.