I have no problems with my Droid 4 and my Galaxy Tab 10.1 together. Absolutely seamless.
Using my Droid 4 tethered to my laptop, however, I find that sporadically my laptop doesn't see the phone at all. Particularly, if my laptop isn't next to my phone with WiFi turned on and searching at the time the hotspot becomes active, the hotspot SSID never shows up in the windows network list. Also, 60-70% of the time after my laptop connects it can't get an IP address from the phone. Most reliable solution is to go to a command prompt and do an ipconfig / release followed by an ipconfig / renew. Once connected with an IP address, I've never been kicked off or had any further problems.