I hear you on the lack of consistent HTTPS. For the very security conscious, that could definitely be a problem. I don’t use Springpad as my main tool, either, so there is nothing I would consider sensitive in there. For what I do use Springpad for — keeping track of things that interest me — though, I’ve found it to be quite useful.
A better test editor would be useful, as would numerous other small things, but I really do like how they are progressing.
For me, the ultimate would be some sort of bridge between Springpad and Evernote, as I believe that they can coexist quite well — and from what I gather, the folks at Springpad are working hard at differentiating themselves more and more from Evernote, so the next few months to a year may prove very interesting indeed.