I just started using (testing) this product in my organization's network, and am so far very impressed. I was trying several others out before I found this (Zenoss, Spiceworks, Hyperic, etc), but none have provided the functionality I needed. I hated that they were all server-focused and only really provided the ability to view information. With the custom actions (combined with psexec and nircmd), Lansweeper stands above them all. I have seen some commercial software that provides alot of these functions, but the cost is ridiculous ($100 per node is not feasible when you have 500+ nodes).
There are just a few suggestions I have that would make this the ultimate product :
1) Use WMI instead of registry to gather information. I don't like having Remote Registry enabled.
2) More interaction with AD. It'd be nice to, instead of having to run the lsclient on each computer you want monitored, just pull in a the list of computers from AD. It'd also be nice if it would report OU's when viewing users and computers. I imagine this wouldn't be that hard to put in myself, but I haven't spent all that much time with it.
3) Along the same lines as above, more control of AD. Renaming computers, resetting passwords, add/remove from group, etc. would all be great features as I'd imagine most people using this are doing tasks like these on a regular basis (at least, I know I do)
There are a few others that may occur to me in the future, but all-in-all, it's a great program.