I'm very happy with my Finis Hydro Tracker, and I've now managed to iron out the kinks that I encountered early on with it. It gives basic pace info, post-swim, which is pretty useful for learning to match pace to the feeling of a particular pace. This is handy for a determined one-pace swimmer like myself who is trying to reform.
But what is also becoming clear is that my attention does tend to wander, causing me to drift off in the wrong direction every so often, requiring a significant correction. The top pic is from this morning, at Lake 32 at the Cotswold Water Park - a momentary lapse on a beautiful day. The bottom one was Bosworth Water Park a month or so ago - I really wasn't firing on all cylinders on that day (but is it just me, or did I draw an owl's face?).