I held off on upgrading from Snow Leopard for some time but finally made the jump on our late-2006 iMac a few weeks ago. Since then we have had random, intermittent crashes that seem to have no pattern based upon Console logs, apps used, etc. I’ve purged much and it continues. Our home theater Mac Mini (2010 I think) has fared better but has still suffered crashes. My wife refuses to let me near her Macbook Pro with Lion. That is probably reasonable since a category of Macs that Lion has treated poorly is the MacBook Pro according to forums I’ve read (search Google with “Macbook Pro Lion crash freeze”). I have to say that the Lion experience has been the most difficult OS-transition I’ve seen on a Mac for years and makes me feel like a Windows user at times. No fun.
I’ve known the iMac needs replacing. It will be put into sunset mode by Mountain Lion which excludes it based on specs. The question as to what to replace it with allows me enjoyable contemplation in idle moments.