When I started hammocking and was experimenting with a tight budget, and before I found hammockforums.net, I used some plastic like one would put down before painting. It didn't do very well at all and I woke up very sticky and clammy. I know now I was "doingitwrong" all over the place.
I then migrated to using a poncho just as you have it before I got my current Speer Winter Tarp. I found the poncho to be a little small for my hammock and I'm not sure how dry I would've been, had it rained on that trip. (My hammock is just to the right of the big blue tarp)
Now I have plenty of coverage for when I need it, and I can rig it so the doors are open if I want a little more view and it's not very weathery outside. Also, it is big enough that I can fit both mine and my fiance's hammocks under it. If I was going to solo all the time, I would probably get something with removable doors for when the weather was going to be nice.
I am pretty happy with my tarp, but I'm sure it won't be the last one I get. I don't really need
another one, but options (and gear) are always nice to have!