As mentioned, you'll need to makes sure that the freqs you want to scan are in the receive capability of the radio, which is limited to 136 - 174 MHz & 420 - 520 MHz. Some systems (like here in Carroll County, MD) they have a VHF simulcast of the main Fire dispatch. I can hear the initial call, but not any on-scene activity which is only on the Trunked 800MHz system.
Scanning is not the fastest. It's all dependent on how many channels you're scanning. I've never tried to change what channels are scanned using the front panel, just via the PC software. There is a Priority channel setting, but I've yet to try it. It's more useful for finding which Ham repeater is active since conversations tend to be long. A quick Police or Fire call (those guys are good at keeping it brief!) may be completely missed if you have more than a couple of channels being scanned.
There's also no "close-call" type of function. You can scan based on any supported frequency and step (e.g. start at 144 MHz and scan up in 5.0KHz increments) but unless you get lucky, or the signal is on the air continuously, it's hard to catch it that way. And there's no limit other than the programmed edges of the band, though you can manually reverse direction.
That said, the PC software (in my case, the excellent KG-UV commander) is very simple to use. Plug everything into a grid that looks like a spreadsheet and Write it out to the radio. It's nice being able to save different versions for say, travel out of region.
Front panel programming is not really intuitive, but there's good 3rd party how-to's out there on the basics (programming a Repeater split for instance). Annoyingly, it's not easy to make a small change to a programmed channel (that I've found) if for instance you want to change the bandwidth or CTCSS/DCS code on the fly.
It's a decent little VHF/UHF transceiver that happens to have a scan feature. It's not going to make a scanner junkie happy unless they're moving up from an old crystal controlled Bearcat
And even then, since it's FM only, you're not going to be getting things that sill run AM, like aircraft.