Lion is not Vista. Vista (IMHO) had a rotten core where as Lion doesn't. There are, however, issues that I suspect will be fully resolved via another update or two.
When I upgraded to Lion I experienced a few minor stability issues (particularly with Finder) so I performed a clean install. Have had no issues since. I would be curious to see stability of a machine that has been upgraded from 10.5 -> 10.6 -> 10.7 vs one that has simply had a clean install of 10.7.
[EDIT as I got downvoted presumably for knocking on Vista]
Vista shipped with the version 6.0 kernel. This was known to be a fragmented, "consumer grade" kernel largely based on Win XP. The 6000 kernel build had so many issues that SP1 completely upgraded the kernel to the improved 6.0.6001 which was essentially the Server 2k8 kernel. It was an improvement but too little, to late.