I bought the Samsung Hotspot Pro for this (I'm in the early stages of a contract with Sprint) on the cheapest plan ($20/month). I've used it in Turkey, UAE, Singapore, Japan, Korea, Indonesia, and Germany and it has worked great. Haven't had to do any setup or change networks - I simply turn it on and wait for it to find a network. Speed is fine for Web, messaging, Google Maps. I even got a VOIP phone call and that worked fine too. Haven't done any speed tests, but I don't have any complaints.

The hotspot is a little large for what it is, but I do like that it can be used as a backup battery. Battery life has generally been good (good to me = lasts a whole day without being recharged) - most days I can turn it on in the morning and when I get back to the hotel I still have half the battery left, so I could also charge something else if necessary. Other days it seems to drain very quickly (I presume it must be searching for service a lot) and only makes it a few hours.

Overall this is an amazing deal!