<p>Is there anyone using Subsonic with asp.net mvc framework? If so, can you tell us something about your experience. Are there tips and tricks that can be shared?</p>

If you're planning on doing database first design, and you don't need any mapping (i.e. you're in control of your db naming) then SubSonic is a decent option.
It's straight-forward, doesn't hide a lot from you.  On the same token, for advanced scenarios I have to side-step it a lot and execute raw sql (or a sproc).
If you're looking for a better object abstraction over the database, something that more closely matches your problem domain, then I'd look at NHibernate or Castle ActiveRecord.  This gives you a lot more flexibility in how you want your object model to look, and you have a powerful query API at your disposal.
None of this really has to do with ASP.NET MVC, other than you just use your objects in your web project.  I'd suggest putting the entities inside of a separate class library project anyway.