Since installing 2.2 I have had no issues with the phone locking up, I never really had problems before though. That also goes for the other people I know that have the Acclaim and did have lock up issues. 2.2 seems to have done nothing but good. There are a couple little quirks out there that need to be fixed but nothing that seems major to me.
The Acclaim is a low end Android phone. There are better options out there but the Acclaim's price is tough to beat. So if you don't have the money to spend on a more expensive phone but still want a very functional phone that will do most productivity/office type stuff without any issue then this is your phone. My best suggestion would be to go into the store and handle all of the phones you are considering. This will help you identify the little details that matter to you in a phone.
However, the phone is still lacking flash support and probably won't get it. It also struggles with or doesn't run more resource intensive games that would normally run on another handset. I don't play a lot of games on my phone so not really a big deal to me.
Some of my favorite apps on the phone that I use all of the time that work great are: AudioGalaxy, Dish Network Dish Anywhere, Pandora, ScoreTracker, Google Voice for Voicemail, Youtube, and I used to use Last.fm until they decided they wanted to make mobile users pay for their service. Tons more apps out there that work great on the Acclaim but those are the ones I use all the time.
Hopefully that gives you a good overview of what the phone can and can't do.