Is an X360 worth it without going online at all? Yes. It still has the biggest, best amount of offline awesome games. Many games are offline co-op, and are fun.
Is it even better to have an intenet connection on your X360? Heck yes. The X360 vastly outpaces every other console in terms of free content - demos, patches, and many other cool things are always free. You don't pay a dime for 99% of demos (the only ones that are pay-for are OXM disks) and free patches. XBL gives everything a whole new huge depth.
Now, as for the $30-$50/year for gold memberships - it's a great system, but isn't needed. If you can't live without online multiplayer, and don't want to pay $3/mo, then I don't know what to say. I've had an X360 since Nov 22nd 2005, and I've NEVER played online. It's still a great system without it.
Back from the dead, I'm afraid.