Most of the time when I see people talk about SWTOR's PvP in general, I see moaning about how it's not balanced enough or about how the devs don't provide enough support for players at the high end. I'm not saying that many of those complaints aren't justified in some way. As someone who plays it more casually - as merely one of many activities in the game that I enjoy - I really love it though. Let me tell you why:
1. It's easy to get into and the difficulty increases gradually.
In case you don't know, there are currently three brackets in SWTOR's PvP: the lowbie one from 10-40, the "midbie" one from 41-64 and the max level one for 65s only. I've spent a lot of time in all three, and they all have a very distinct feel to them.
Lowbie is by far the easiest to handle and a good place to learn for new players, because while you get into all the same warzones as a max level player and may still come up against more experienced opponents that just rolled an alt, everyone has comparatively few abilities, which makes both learning your own skills and those of your enemies a lot more manageable. You don't have to worry about all your attacks failing to land because your opponent just chained three survivability cooldowns in a row or people using different utility skills to zoom across the map with what seems almost like impossible speed. You have time to get to grips with your own class and with the objectives, and countering enemy moves is fairly straightforward.
Midbie is a clear step up, and depending on how close to 65 most members of both teams are already, you might have to deal with a good chunk of the same abilities that max levels also have. However, it's still somewhat more forgiving than the max-level bracket, and you don't have to worry about gear disparities.
At max level the difficulty is definitely somewhat ramped up and you need to start acquiring actual PvP gear, however they lowered the price of the basic set by so much that you can buy it after only a few games (or even right away if you've PvPed while levelling). Warzone commendations can also be transferred between characters of the same legacy, so if you already have a well-geared character on whom you PvP regularly, you can use them to give a new alt a leg up.
All that said, if you find that the next bracket up is too difficult for you, you can stay down in the lowbies or midbies if you want. While there is no option to stop XP gains, rolling up a new character and getting it to level ten to get back into the lowbie PvP action takes no time at all these days. (Some of my guildies have done it in less than an hour.)
2. Lowbie PvP actually happens.
It may sound strange to you to point this out if you're someone who's used to World of Warcraft, where any queue longer than ten minutes is already an outrage, but other MMOs don't always have the population to keep all the different content queues running at once. If you frequent the forums for games like Rift or Wildstar for example, you'll see people telling newcomers quite emphatically that PvP while levelling simply doesn't happen (despite of cross-server queues) and they can't expect a queue pop until they've hit max level. In SWTOR this can be a problem on the less populated servers too, since the queues are not cross-server, but if you roll on one of the bigger servers, the pops for any of the brackets keep on rolling all night long.
3. Class balance is pretty good.
As Yahtzee famously said in his review of SWTOR: cows go moo, dogs go woof, MMO players go "the PvP is unbalanced". No game ever gets it completely right, and as someone who plays all three healing classes in PvP I can tell you that Sages are definitely far more powerful right now than Commandos or Scoundrels, and that while being a lot easier to play to boot. However, if you look around the MMO space a bit, things are actually worse in a lot of other MMOs: class A doing literally twice as much damage as class B or some classes being virtually indestructible while others get one- or two-shot, not to mention the ability to pay for power in some cash shops. None of that is an issue in SWTOR. If you want to dip your toes into ranked, class selection becomes an issue for sure, but in regular warzones where people generally aren't very organised, you can have fun with any class and spec.
4. Plenty of different warzones from the ground up.
Most competitors limit a lot of their better PvP maps to higher level characters - for example in WoW, you won't get anything but Warsong Gulch and Arathi Basin until you're level 35. Not so in SWTOR: all seven gameplay modes are available from level ten onwards, guaranteeing fun and varied pops from the start.
5. It looks cool but isn't too tiring.
I see a lot of hatred for tab target combat in comment sections these days, but personally, action combat isn't for me. I've tried it and I do play Neverwinter too for example (which does have action combat), but I find constantly having to kite and dodge extremely tiring after a while. I like that SWTOR's classic hotbar combat is far less demanding in that regard, but is still visually engaging because the animations are very good and fun to watch (lightsabers go whoosh!).
6. You meet a lot of funny people.
OK, this isn't really related to the PvP itself, but I still have to mention it. While you can run into a lot of weirdly named characters on the fleet, I always get the impression that PvPers are the kings when it comes to giving their characters stupid names or dressing them up in ridiculous costumes. (Maybe because they are less invested in things like story, lore and immersion?) Either way, it's rare that I load into a warzone and don't immediately spot a name or look that makes me go "What the...?" It's a nearly endless source of amusement and can do wonders when it comes to taking the sting out of a bad defeat.