The serial decoding is great. It was first introduced in a beta release over a year ago, and has improved in many steps since then.
The decoding (both UART and SPI) is now fast and reliable, except for the last char in each sweep. For SPI, the last char is often decoded to 'unknown'. I first got a shock, because I thought, there was somthing wrong with my hardware, but then I noticed, that it was always the last char of the sweep, and therefore, I could concluded that it was not my hardware, that had a problem.
A part from the bug above, there are a two things that could be improved:
(1) The 'signal idle state' setting on UART decoding is default set to low. This should be changed to high, this is much more common.
(2) The 'bit order' setting on SPI decoding is default set to LSB first. This should be MSB first, this is much more common.
Alternatively, save the decoding settings with the startup settings.
Having the SPI/UART settings in a extra window behind, helps to keep the interface clean looking, but these settings are very important and when they are out of sight, they are out of mind.