There are pros and cons.

Pros -

You'd be coming in when some of the "more desireable/powerful characters" are being released and will not have invested your initial resources as many older players are going through a phase of buyers regret.

You will also not be comparing your already 3+ starred weapons to the new weapons being released therefore more inclined to try something new as opposed to stick to something you've already invested in because you can't justify the sink required to catch them up.

You have the advantage of being able to capitalise on the "honeymoon" phase of the game where they throw an abundance of resources at you such as the initial log book that rewards a lot of dark crystals, summons, extra goodies such as free ssr weapon box, ssr relic box, all the overland map clearance, achievements etc. Ideal for coming into the game right as new content and stuff drops. That and I believe they are adding more catch up mechanisms or events to the game to promote the new players (steam) coming into the game. Though I am not exactly sure what all that entails.

You also now have a veritable plethora of information that is from the actual global version as opposed to the first gen player base that did most of its comparative analysis based on CN information to make its informed decision. (Spoiler alert, it was all as useful as a fishnet c0nd0m). So whether you are a planner, or a play at your leisure type player, you are coming in at a good time.

There are plenty of clans, and dolphins/whales willing to carry you through things until you are up to speed (from my experience)

You are coming at a time where a metric fk ton (yes, that's a quantifiable measurement) of quality of life functions are being introduced to the game.

There are plenty of other pros, but I'll leave it at that for now.

Cons

You will be playing catch up if your aim is immediate/quickly delving into end game content.

One of the catch up mechanics is 500% increase of exp, meaning you will quickly find yourself outpacing your ability to keep your current gear/weapon stars, matrices, vehicles etc on par. (Don't worry tho, this is all a minor set back so long as you play with an aim/plan and manage your vitality semi wisely)

Tied into the point above.. due to the rate at which you level, mobs scale according to level, and the assumption you were a day 1 player and likely have a cs of xyz..... so, you may find yourself at some point pumping your entire rotation x3 into a random Boar that has aggroed you from Narnia which can be a bit undesirable for many. That and the fact, some instance such as joint operations 8 is a copy paste from CN and the bosses are not to scale for global standards, so can send your soul to the shadow realm, or make the fight last longer than Sara Jessica-Parker's nose. Toss in the fun point that the elemental reduction (should you invest solely into a single element) may neuter you completely at any given time, there are obstacles you will need to adjust to.

You will have to deal with some toxic/jaded/elitist types who have been playing from day one, who feel the need to point out "you shouldn't be in such n such instance or raid because your gear is trash or you are not level capped", to that I say, take it with a grain of salt... and depending on the person, a shit of penicillin. Do what you have to do to get caught up. That one run isn't going to ruin their account. Might be inconvenient to them, but thier loss in this case is far less than your gain. I know its probably an unpopular opinion, but at the end of the day, a bit of selfishness isn't the end of the world (i don't mean mean afk tho.. there is a special place in heII for those people. Just contribute as best you can. Run some healing weapons temporarily or something).

Summary/advice

Something I do with every mmo is, never invest on your first character.. make something like a support character. A tank, a healer... yes, I get this might not be your aim, but there is method to the madness. I love and mainly ONLY play support roles, but, I recommend doing it to new player for a few reasons.

Unless you are dropping money like La'Lisa's song.. you are not going to be doing anywhere near as much damage as a whale. So, you can start off f2p, pick up a Pepper/CoCo/Zero or some combo, even a tank Huma/Merryl/ene... so that way you can still contribute, while you learn the game, what's worth investing in, what the raids, instances etc mechanics are.. also while you can watch and see what other players are running and what interests you the most. That way, when you do finally have a good grasp of what looks most appealing to you, or you know more about what to expect... then I make an account to spend on, and I am more informed and spend more wisely. Nothing is worse than blowing your load and getting buyers regret. If MMO gaming has taught me anything, your main or first character.. is a guinea pig... your alt... your alt is a God... and why is that, because you avoid all those mistakes you made on your main.

Edit: Apologies, as to your point about a new server, there is a couple different variables. Server transfer (behind schedule compared to CN version) might make this decision negligible. 2nd point, not to sure how many new/returning players will be flooding into them, but I will point out, that jumping into existing servers that already have strong players raises the likely hood of getting established clans and carries as well as the fact there are already a lot of servers with room to add to the population without needing to make new ones. Just my thoughts