This is a brief assessment of Neverwinter Online having played it now on two occasions using two of the 4 classes it currently allows: Mage and Rogue. I haven't tried Cleric and Fighter and don't expect to. In both cases I played up to about 15th level taking several hours. I have posted this assessment also on the Bioware NWN2 forums in this thread.
I have very limited experience with MMOs other than SWTOR (Star Wars the Old Republic) which I have been playing for a year and now have 18 created characters on three servers. I also briefly played DCUO (DC Universe Online) and played for only one evening WoW (World of Warcraft) and STO (Star Trek Online).
For starters, I found the character graphics to be terrible. They look like NWN. That was fine in its day, but they should look far better now. As in any MMO you spend all of your time looking at your character's backside so it is important that they look good. They just don't. And you have very few options as far as armor or clothing and almost no customization ability (there is a way to dye armor but you have to find the dyes). DCUO does this best because you can easily create very unique looking uniforms and each time you get an item you get to keep the look of it if you want to even if you switch items. SWTOR is ok at this because the graphics are sharper and the number of clothing types is fairly large. But in Neverwinter everyone just looks bad.
Combat is incredibly repetitious. My mage could shoot an infinite number of magic missiles by my just holding down the left mouse button and all I needed to do was change who I was aiming at. You have only a few types of special hotkey attacks (by comparison in SWTOR you have well over a dozen) so you find yourself watching the cool downs all the time to see if you can use one again or have to go back to the left or right mouse button attacks that always work. The one feature I liked was that as a Tiefling I could teleport myself short distances while fighting in order to attack from behind or avoid being hit. This involved holding shift and pressing one of the WASD buttons. I found myself constantly hitting CAPS LOCK instead of shift and never got very good at it.
The UI interfaces are all lacking compared to SWTOR. In SWTOR you can bring up the map and turn your character while the map is shown, and even move your character while the map becomes semi-transparent. Not here. While the map is up you are frozen and as soon as you move the map is gone.
The follow-the-sparkles way of getting to quest areas was buggy. I had to frequently press the Z key to make them reappear. And sometimes you just have to walk around blindly until they show up. Again, the SWTOR map and functionality is far superior.
Unlike SWTOR where the areas are huge and you can easily navigate around mobs you do not want to deal with, Neverwinter is cramped - almost claustrophobic - and I often found myself accidentally fighting 2 or 3 mobs at a time just because while fighting one mob I accidentally got too close to another. There is no death penalty though, you just get sent back to the last healing campfire you used.
The UI for shopping is also inconvenient. Things that should be simple are not. Like the fact that to start a conversation with a vendor you need to press F but to end the conversation you have to move your mouse to the "Finished" button instead of just pressing F again.
While I only experienced 2 crashes to the desktop, I had to logout and back in several times to correct odd graphic glitches. Most irritating is that after being killed my character's running would be affected. Once he was running sidewise all the time and another time he looked like he was moon-walking. Logging out and back in was needed to correct this.
I also experienced a large amount of rubber-banding, which is when you are running and all of a sudden you are moved back a second or two from where you were. This happened all the time and in some cases I would end up in a completely different room of an interior.
The nice thing about the game is the chance to see what 4e Neverwinter should look like. That should prove useful as I am (still) working on my Gems of Power campaign which takes place at the same time as Neverwinter and the city of Neverwinter was going to be one of the cities I allow travel to. Of course with the NWN2 toolset I won't be able to do everything, but I think the visuals from Neverwinter may help.
I haven't been able to use the Foundry yet, but I'm hoping it offers a decent alternative to the NWN2 toolset. I am certain the NWN2 toolset will be more capable, but the reality is that if you want people to play something you build you have to use the platform they are on. Besides, maybe if some of us NWN2 modders build some good Foundry content it may lead people to try NWN2 out.
I don't see myself ever being a regular player of Neverwinter though.