Apologies if I am repeating what others have already reported, just trying to gather my thoughts in one post. Core i7 rig with 8 GB, used to have an Nvidia 8800 GTS, now a GTX 570, Windows 7 x64. After a number of games when the moneyball lose animation plays the game will loop sound and freeze, alt tabbing or using ctrl-alt-del will show the mnc.exe segfault message box on the desktop. Buying bots as an Assault is often problematic as the Buzzers get stuck on high walls before they even leave your spawn. Maybe the 1, 2, 3 skill/colours work for Xbox as they map to the controller's button, but for PC it's not immediately clear what shift/q/e map to. As Support healing a turret or a pro it's difficult to see the healthbar as it tends to be cut off at the top by the letters used for the name. Lobby chat, when you type in something into the text entry box before teams are made, and then the teams get sorted it will reset the state of your text entry box, effectively wiping all you typed and you get to restart. What's up with teams being made of all high-levels on one side and many low-levels on the other? This has happened quite often now and it's quite a negative experience for these newer players since they tend to get steamrolled. Support's heal/hurt gun has a lot of problems of triggering, even when you aim it at a player, bot or turret. It's like the area where you have to aim is quite small. But also when you try to use hurt on others it does have difficulty triggering. Churros and Bacon do not have any indicator of what they do. You pick them up but without reading about it somewhere the game has no visual feedback for what I could discern. In the server lobby, when you use the mousewheel to scroll through the server list it seems as if it will poll the server for the server settings. Since you are pinging and polling the server anyway, would it make more sense to do this as the server list is populated? It will save the server from additional hits as you scroll/click through the list. Not to mention, make scrolling through the list much more fluid.
Ah yes, some more: The tank's railgun has some difficulty on some maps. When you are on the top level in and try to shoot someone through one of the open hatches/windows with the railgun you are shooting against the bottom part. Effectively it blocks your fire. When you try to connect to a server that's full, the client will try to connect anyway (which I can understand due to maybe the server having freed a spot in the mean time), but when it's still full, why does it drop you back at the first screen of the game rather than back in the multiplayer/server lobby?
At the end of the match your cash and level gets increased and the level bar makes a wobbly sound as it fills up. If you close this window before it is done filling up the bar, the wobbly sound stays looping in the background until it refreshes to the loading screen and resets the sound buffer to play the loading music. This happens on an X-Fi.
A possibly-related problem I have is that it seems like you have to wait a second in between switching heal/hurt targets, or you'll end up with nothing happening at all while you hold down the trigger. I'm used to TF2 where I can instantly and rapidly switch between healing targets
That might actually be more the behaviour I am observing. Like you, I also play a fair deal of medic in TF2 and as such I am used to overheal switching being relatively fluent. Then again, I also had my heal gun suddenly have a thread go up to the ramps to heal one of my allies, even though I was aiming in front of me.
A bug I only encountered once: turret on LazeRazor in our base was broken, nub spawned back into place, none of the players on our team got the buy popup any more for this turret. So until the end of the match we were permanently crippled in defense.