Having "enjoyed" WT once in long haul on a day outbound and a night inbound, I would agree that it's OK for a day flight and you can tolerate the person in front of you reclining their seat and the impact that has on your space.

On a night flight, I found it unbearable and arrived in London in such bad shape having had no sleep (mostly due to a lively passenger in front of me and that I find it hard to sleep when flying).

I haven't experienced WTP yet but for under £200 and an overnight flight I would definitely do it.