I have decent .net dev experience and 3 months on SP, my experience so far:
The good:
I think SP is good for application with simple data model, preferably read-heavy. A huge strong point is what users/administrators can achieve with configuration only. Change data structure on the fly, modify look and feel, etc. A wonderful platform for "my books" kind of things..
The bad:
But there are lot of things where SP stumbles and falls (on you). For example it is hard to work when non-trivial logic is required, especially aggregation functions over foreign key relationships. And of course the lack of transactions. Maintaining data integrity could become a problem. Beware of this when you consider working on a specific project.
There's little compile-time support, majority of your tasks will include messing with resources looked up by calling it by name as a string. It can be considered "flexible" and "simple", but its just too error-prune for my taste and slows down development. Of course this is not only SP thing, but MVC/webforms seem more easily pushable toward the strongly typed world.
If you like managed world then deal with the fact that the vast majority of SP is non-managed code, giving you exceptions like "HResult 8000072F" with next to no stacktrace to hint you on what could have failed.
Deployment and bug reproducibility has caused quite many frustrating days. WSS takes the whole machine for itself, files needed to run the app are scattered around DB, file system (and quite often GAC). To have a basic separation of projects, expect to be working on lots of different VMs.
The tool support is quite poor (not tried VS 2010). Better expect to make friends with command line and scripting. Expect debugging experience to be slow. Unit-testing is quite hard to do..
My personal conclusion:
SP has it's niche but it is not a platform a .Net programmer can enjoy. The user experience may have some occasional "WOW", but the developer experience did not. This could be the "steep learning curve" talking, but maybe it's just the way it is.