I was the 1st person to download aMaze GPS for Blackberry. I had used it on a Sony Ericcsson phone briefly and hounded them until they released the BB version.
This is what I found, everything is fine as long as you only use the turn by turn screen, but the map view never quite catches up when navigating. Also the user interface is very difficult to navigate, way too many key strokes for my taste. Unfortunately I have gone back an redownloaded the program repeatedly over the last few months and things have not changed. Also I live here in NE Indiana and their map database is inaccurate in spots. It will try to route me onto an interstate hwy that has no access from where it routes me. I reported this problem to aMaze back in April 2007 and its still not corrected. On their behalf I will state that they receive their map data from outside source (and not one that the big boys use) so it's not the aMaze teams issue. Also when I missed a turn once (on purpose) it tried for 4 miles to reroute me back to the original route, even though I was headed home on a direct shot route. I love the possibilies this program has but for the time being it just has too many issues. I have deleted it, multiple times.
With this being said, other areas of the US or other countries may have more accurate maps than is here in the midwest. Try it out, the aMaze team works hard and deserve a chance to prove themselves. Its free and it will eventually get you where you're going, unfortunately for me, it stressed me out. LOL I went to Telenav and now to Mapquest, it seems to fit my tastes the best so far.
BTW I believe the map lag is due to too much information on the mapscreen, too many fancy details. If they clean it up and pare down I think the program has great possibilites.