I could have had a glass roof but, at the time I built it, there was a neighbor's tree hanging over it (now removed). Also, I was a little afraid of the heat in summer with a glass roof. The glass has some sort of UV protection to filter out some of the heat but I wasn't sure it would be enough for summer. So I went with the solid roof. One side of the sunroom faces south so a lot of sun comes in, especially in winter - but the tradeoff is the UV filtering in the glass makes it less effective for plants.
So it's not a perfect
solution if I wanted a real "greenhouse" for plants but it's a decent compromise between a greenhouse and family room. In summer, most of the plants go outside and it becomes more like just a screened porch (all the windows and doors open and have screens).
But back on the subject of UV filtering, there is enough sunlight coming through to keep most plants happy. As an example, there was enough sunlight coming in that I was able to get these poinsettias to re-flower.
Not greenhouse quality but they re-bloomed!