Edit: (This review doesn't touch on the predatory MTX/F2P nonsense, there's plenty of good reviews covering that, so I'm just going to cover how this is not the same game I came to expect from the beta.)
So I've put some more time into the game now, and while I'm finding some amount of fun just goofing around with my buddy, it just doesn't have that same magic I experienced in the beta. I've gotten a better flow for combat, and 2v2 is sorta a chaotic mess not too different from before, with the reduced speeds making it harder to switch targets for a quick team combo. In 1v1, the pacing seems to play a patient start of landing a hit and then guessing if your opponent is going to dodge or attack, determining whether you delay your follow-up attack. You do this until your opponents dodge meter is drained, then you can finally get aggressive and go for combos. This is how most characters have to go about it. Some characters have much better true combos even when the opponent has dodge meter. Otherwise expect a lot of short 1-2 hit interactions and then watching your opponent run to the opposite end of the stage for a hard neutral reset. Not my cup of tea, but some people still like it.

Original review: Let me start by saying I put nearly 400 hours into the open beta, and it was the best time I've ever had playing a game. As you might expect, I was extremely excited for this game's return. However, my early impressions are that this is more like a sequel, and good example of how the beta played compared to the current release would be to compare Super Smash Bros. Melee to Smash 4. For some people, maybe this is a good thing, but I miss the high speeds of the beta. My final caveat for this review is that 99% of my time in the beta was 2v2 with a friend, and most of my (short) time in the release has been 1v1.

The game has gotten slower. Interactions between players happen less often, combos are shorter and characters generally have fewer reliable ones (its still early, so maybe people will be finding good combos later). I've been parried in the middle of my automatic jab combo simply because I delayed a hit for a couple frames. While the game is slower, characters die at earlier damage than ever, possibly to make up for the slower gameplay, or possibly because characters are larger.

While characters are larger, stages are the same. Many characters heads are now level with platforms, making platforms an obstacle to get around to return to the floor rather than a temporary landing zone. The camera is also zoomed in really close, negating their original reason for increasing character size: making things easier to see. Combine that with the smoke trails on all knockback, and any visual clarity they gained has been lost.

In terms of knockback, it has become rather balloon like. Characters speed through their knockback at high speeds, then rapidly decelerate at the end of it. Knockback also seems to come in two flavors: short range with laughably low hit stun, or stage-spanning distances. So, interactions boil down to a passive neutral game, a short 3-5 hit combo, then back to the passive neutral.

Many abilities were also changed, limited, or removed, like Shaggy's sandwich, Superman's up special, and Finn's gem, respectively. Dash attacks were added, affecting approaches in a pretty dramatic way. Some characters have great dash attacks, but on those that don't I found myself wishing I didn't have the move at all, as it just gets in the way.

Parrying has also been added, replacing the spot dodge. Admittedly, spot dodge didn't get used much in the beta, but towards the end of its life span I started using it a good bit more. Since it now does a parry, the dodge frames on it are nearly non-existent, so the option of dodging in place has basically been removed unless you have excellent timing or ping.

All I wanted was some polish and more content, but I feel like I got a completely different game instead.

TL;DR: New players, give it a shot. Open Beta players, you're getting a different game.