Yeah, it usually works pretty well. The disassociate and reassociate time is only around 1 second or so.
Depending on what you are using, it should be pretty seamless. I've tested it in my house a bunch since I have a router at one end and an AP at the other end. File transfers, web page loads and such forth pretty much are always seamless, occasionally you'll notice a second or two "hang time" on the file transfer before it resumes. Rarely it'll just hang (I think I've seen it happen ONCE on my laptop, in about 40-50 occurances of roaming between on laptop, tablet or phone).
Streaming video usually works pretty well to, as most cases it is buffering at least a few seconds, depending on the service, or more.
VOIP can be buggy though, same with video conferencing. With facetime I've had it drop the connection twice in about 5-6 times and skype I've had it drop once in the maybe 3 times I've wandered between.
Outside of VOIP and video conferencing it is generally pretty trouble free.
My suggestion is to turn up roaming agressiveness to the max on whatever devices you have. At least I have no issues with it and it tends to switch sooner, which is often better. Of course things like iDevices you can't do anything, but anything Windows related you can.
Broadcom drivers you want to set roaming to Max bandwidth (NOT range) and Intel is just aggressive. There are, I think another setting on both you can tweak (how often it looks).
Basically both Intel and Broadcom on the most agressive settings will start looking to connect to another access point once the dBm strength hits -60 and on most agressive settings will connect to a network only 10dBm higher in strength. On the least agressive settings they won't roam until -80dBm and the network has to be at least 20 (or maybe 30?) dBm higher even then. I do NOT recommend that at all.