The Open Beta seems to have been a much improved experience over the closed beta. However, there are still some thoughts I have to add. These have to do with Bots, Hero Select, the party system, and general balance.
Bots: The AI is actually pretty solid. I'm not an amazing player, and bots in pvp games often felt strong enough to not mean 'the end' for the team that had the AI. However, i also experienced a LOT of people leaving as soon as they'd died. Perhaps some sort of punishment for those who disconnect from games prematurely? The AI may be good, but I don't think one can really argue that AI will surpass good players.
Additionally, I experienced an issue several times. Hypothetically, imagine playing elimination. You square up against the person you spawn next to. It's a bot. You engage it and fight. You get it low. Then, someone joins the game, replacing the bot. The bot vanishes, and the person who joined starts at full health, and doesn't even spawn where the bot was. What? That's so much BS. Should make it so if you replace a bot, you have to wait until the next round.
Hero Select: This one's simple. I want to see what my team is picking. As time goes on, I'm sure some level of a 'meta' will develop, and being able to see what my team is picking, so I can pick accordingly, would be very nice and helpful!
The Party System: Better than it was in closed beta, I still found the party system, and the multiplayer queue, clunky and odd. The 'feature' of kicking you out of queue if too many players leave a lobby is annoying and asinine. It's annoying having to requeue almost every game, because people often want to find a new lobby. Additionally, if you're playing with a friend when this happens, and they're in your group, it disband the group for some reason. So if a game ends, and everyone leaves the lobby, and the group leader doesn't manually leave, then you have to re-invite the friend(s) and requeue. Annoying.
General Balance: I'm not an amazing player, so these are just my impressions, and may be woefully inaccurate: The classes don't feel balanced. Obviously, perfect balance is a pipe dream, however, I don't think getting 1-shot by a 4th level feat (The bomb/mine thing) that was just planted in the ground is stimulating or exciting. Meanwhile my 4th level feat was aoe heal DOT, or unblockable attacks, which SOUNDS good, except everyone can just run faster than The Kensei and wait for the ability to expire.. I primarily played Kensei, and perhaps I was just up against better players, but I often felt that there were certain classes that I just didn't have options against. Being the only hero I was THOROUGHLY familiar with, against moderately skilled players, his moves are simply too telegraphed and obvious.
TL;DR:
Bots: Need leaver penalty, don't replace AI with player mid-round.
Hero Select: Let me see what my team is picking/thinking about picking, so I can pick accordingly.
The Party System: Don't kick me out of queue when a lobby expires. Make it so a group survives being kicked out of a lobby due to dissolution.
General Balance: Waa waa so and so is OP. (For real though, Kensei needs more options if you want him to be viable higher up.)