A few things to update here as Vueling are constantly changing their fare/product names and conditions.

They now have three levels:

Basic - this is exactly what you think. No checked bag, no seat selection, no, changes, no nothing.
Optima - seat selection (in a "bad" seat), checked bag, some flexibility.
TimeFlex - same as Optima but with changeable ticket, fast track and priority boarding. NOTE that you will now still have to pay for better seats. Rows 2-4 are called Space Plus and cost 20€. Row 1 is called SpaceOne and costs 25€. There is no longer a blocked middle, there is no longer any catering. They can and will pack them in 3 across. Also note that these Space One seats have the tray tables in the armrests, so they are about 5cm narrower than the other seats. The only way to guarantee a free middle is to buy it yourself. So yes, this is worse in literally every way.

I'll be very glad when they move on from this miserable pricing and onto whatever new shiny thing distracts their marketing team next, hopefully something that resembles a normal, crap European J seat.