I was really impressed by the very smooth process through which my paper on cost-effectiveness analysis in the presence of structural zero costs (which I've already mentioned for example here and here; the related R package is described here) has gone in Statistics in Medicine.
The review process was quick and helpful (at least for one of the referees and the editor $-$ the other referee was kind of not very helpful at all). More importantly, thanks to a recent agreement that UCL have signed with various publishers, the paper can be published in open access $-$ the final version is freely available here.
The only thing I'm not quite completely sure I'm happy about is this: like many journals, SiM has a LaTeX template that you can use while preparing your manuscript. The draft version looks quite neat. But then, when they produce the final version, the maths fonts look more like those obtained using an old version of MS Word. Now, I can see that not everybody uses LaTeX, but once they go to the trouble of re-typesetting the accepted papers anyway, I don't see why they don't do it in LaTeX (which would look much better!).
But I may be missing some trivial point here. In fact, I was talking to somebody from Wiley earlier today, but I forgot to ask...