After playing around with different settings und testing some games, here are some impressions.
First off, mouse input is completely messed up, which is a pity, because apart from that, DOSBox runs surprisingly well - I've yet to find a game that doesn't work.
One thing I noticed, though, is that in Links386 the mouse acts exactly as it should ...
Even though dynamic core hasn't been implemented yet, speed is satisfying IMO, considering the fact that DOSBox is running on a phone (core=simple, cycles=max, frameskip=2). I guess it reaches at least the speed of a mediocre 80386 (depending on the game - Ultima 7 seems very slow, while Wing Commander 1 & 2 work great; Doom and Ultima Underworld 1 are almost playable).
Enabling sound has no noticeable impact on emulation speed
. It skips every now and then, but only very rarely, mostly during file access, which doesn't bother me much.
The onscreen controls tend to block parts of the screen that need to be accessed by mouse (not a real problem right now, as you can't use it anyway) but rearranging them at the right or left border is a good workaround. Text input via virtual keyboard is a bit tedious, but it works nonetheless. Also, keys that are often used, like e.g. (Space), (Enter),(W)eapon, (T)arget etc. for Wing Commander, can easily be mapped to the 6 onscreen buttons.
So all that's really needed for now is proper mouse emulation. Everything else is as good as one could ask for right now.