To deploy or not to deploy on Google App Engine

I am nearing the end of a project I have been working on and trying to
figure out if deploy on the app engine with jruby is a good option.
They offer a tremnedous amount of bandwith, storage, etc so it is very
tempting.

i dont have any expreiences on deploying projects on jruby and was
hoping to get people's opinion on the good and bad of it. Are there
perfomrance issues? Could this lock me in if later if they decide to
release support for ruby?

It is not as simple as running your application in JRuby and deploying
on the App engine. Datastore is different on Google App Engine and
you will need to do significant work to accommodate Google's big table
instead of active record. Moreover, those APIs are Java only which
will require you to write some component in Java to accommodate your
data storage needs.

Support for Rails on App Engine is still very much "proof of concept"
right now; as other posters have noticed, the only datastore available
is BigTable, which doesn't play well with ActiveRecord at the moment.
There's also a number of subsidiary issues (like a low limit on the
number of files in the app [1000]) and very little support available.
Especially if you're at the end of a project, you're better off
deploying to an environment with more of a track record.

--Matt Jones