I think Deadlock is shaping up well but it inherits one of the biggest problems of DOTA 2 for me; matches can last far too long. MOBA gameplay is basically a push and pull situation between 2 teams. The best matches are the ones which are close where both teams are reasonably balanced. The issue is that it sometimes becomes difficult to gain an advantage and push through to win and so matches can last an hour or even more. At this point in life I do not have the ability or desire to play a single match for an indeterminate duration which could last over an hour. They solved the problem in DOTA 2 by introducing a turbo mode which increases your xp and earnings substantially so you get powerful much quicker which in turn lets games end faster. Those matches still take 25-30 minutes though. I hope Deadlock starts with a modifier like this right out of the gate. On a related note, I'm not sure why the map needs to have 4 lanes. The maps could easily be 3 lanes and presumably that would naturally decrease match times.
The game is full of placeholder assets right now. That includes mostly non descript to ugly character models and art. I feel like that definitely needs to be overhauled by the time the game releases. Otherwise it'll run into the same problem Concord is facing which is that nobody likes any of the heroes. A MOBA is not a hero shooter so there is more flexibility in what you can do with character designs but I don't think what they have is anywhere close to good enough for a final release.
I also think they should consider tuning the early stage combat. Typically in these games you start out very weak and then slowly upgrade your character until you become powerful. In DOTA 2 you can buy items right at the very start to mitigate some of that weakness. No such mechanic exists in Deadlock. Secondly, third person shooter combat needs to have much more visceral combat feedback as compared to top down combat in DOTA. What I'm saying is, the combat does not feel fun at the start. Your damage is too low, magazine size is too small, reloading is way too slow. I feel like combat should be a little more engaging even before you power up.
And finally, my gut feeling is that this is not going to be the next Valve hit game. It'll be one of those quietly successful games that make enough money to sustain themselves and be profitable but never big or in the zeitgeist. Games like Smite for example. Maybe even reaching Warframe or Naraka Bladepoint levels, which are actually both very successful games but rarely get talked about. I don't think it'll be one of the 'big boys' unless Valve pushes some levers that I can't really think of. I assume it'll have a very fair free to play model. They could try and jumpstart a competitive esports scene like they did with the International for Dota. They could be generous and do random, free hat drops after every match but for that to be enticing would require a rarity system of hats i.e. lootboxes.
I think the game is quite early but the way they're expanding the footprint might indicate that they're farther along than I think. That or they're planning a long open beta situation. I do think there's stuff they need to work on.