So here are some of my thoughts after using new Cura for some time.
I find the it quite good, but there are things that I really miss from old Cura. I will not delete the old version anytime soon, that is for sure
Regarding speed, new Cura generally feels faster but it is not consistent. It sometimes gets slow and does strange things when I add numerous copies of the same object for example (?).
One thing that is a huge improvement in new Cura is the pan/zoom/tilt-function. Coming from a CAD-program it was a pain to try to zoom in on the layers when previewing in old Cura but in new Cura it works just as one would like it to.
The most annoying thing by far for me (which several people complained about during beta testing) in new Cura is the
scale function where you scale both by putting in numbers and by "dragging". One carefully scales the object and then wants to move it slightly on the platform as in old Cura, and then it goes gigantic or microscopic instead...
There are two more features I would like back too, one is the
multiply option where you could add the number of copies.
The other one is the
split function that splits STL-files that consists of several parts into individual parts.
It is not something I use for every print, but it sure is nice functions when one need them.
I also, as always, have issues related to the
autoslicing. (As much as I know Ultimaker will never make a button to pause autoslicing, I think that is the most needed function of them all in Cura).
One problem of course is that Cura generally gets slow and unresponsive when autoslicing large models.
Another is that move/scale/rotate sometimes stop responding after multiple quick changes in parameters (which appears to have something to do with autoslicing), suddenly it does not matter how much you click on the model, you still can not use those buttons on the left.
Having to click on the model again every now and then to use those functions on the left is by the way unintuitive, one should make it always stick to the last model that was changed or loaded. (I had issues with this trying to teach people how to use Cura lately).
Then
Cura still has issues with large models.
First of all I would like it the old way, when it does NOT autoscale the model when loaded (you can end up wasting a lot of time if you don't notice it was autoscaled). It was much nicer and more intuitive on old Cura when the model simply ended up grey and visually much larger than the printer volume.
Then there is one model that I could slice in old Cura (although it took forever and made Cura crash from time to time) that does not work at all in new Cura:
http://www.thingiverse.com/thing:862724
Not sure where it goes wrong but it is a pity since it is a really nice model to print.
And then one really important thing:
New Cura is killing PLA prints by setting full fan speed at second layer (0.3 mm).
In old Cura it was set to gradually increase speed up to 2 mm (I think) which worked really well.
This is the difference between being able to print PLA on a cold glass plate with glue and not being able to print on cold plate with glue.
I never understood why Ultimaker overuse the cooling fans like this, it is the same thing with ABS, just reduce cooling a bit and you will not have buildplate adhesion issues anymore!
I hope I did not overload you with work now nallath