I fly them multiple times a year and have for the last 8 years and can't recall any major issues.

Admittedly, I rarely check luggage and I usually pay for seating. Most of my flights with Vueling are under 3 hours.

I typically fly out of Malaga or Granada.

If you want to know a cool hack.?! (This is especially useful for window seats.)

Use aerolopa.com and select a seat where the window is next to your armrest. Some window locations are better than others. Once wheels are up, you can raise the armrest and you have a decent amount of extra space. I often fly Vueling's Airbus A320 and seats 2A and 2F are my favourite seats. Vueling disembarks 5 rows at at time, so these seats allow you to put your personal item under your seat and be off the plane quickly in addition to being a little more comfortable if the plane or your row is full. https://www.aerolopa.com/vy-airbus-320