If you have have used Jelastic, chances are, you have also tried one of our competitors. There are a number of them out there. One of the biggest ones is Google App Engine.
One of the main reasons we developed Jelastic was due to the short comings and hurdles that the current solutions available for deploying Java apps to the Cloud had, either inherent or planned. One of the biggest issues is being locked-in to, and having to code for the platform that you wanted to use. With Jelastic, you don't have to worry about that. You are never locked-in; you don't have to code for the platform (because we use standard software stacks); and deploying your app is easy.
One of our users, Richard Bremmer, wrote a short post on his blog (Codezuki) about moving from Google App Engine. Here it is in part:
GAE (Google App Engine) to Jelastic. One of the main reasons I fell out of love with GAE is because it required too many design compromises. I found myself designing my data model because GAE needed it to be that way and not because that's how I wanted it to be. Such design restrictionsare in the name of extreme scalability - however I came to realise that I will probably never need such scalability and in the short term the compromises were hurting my effort. I started looking for alternatives... After being burned by GAE (ok, it was a slow burn over a few years :) I decided I wanted full control and I eventually narrowed this down to two great options. Cloud Foundry is an excellent choice which I strongly suggest you should consider. Being a Mac user and not wanting to spend money on VMware Fusion I decided to look for something free and I eventually settled on Jelastic. The great thing about Jelastic is that you don't have to run any kind of special local environment. When you setup your Jelastic environment you have several database and application server options. I chose MySQL and Tomcat. Now I can build and run my .war against my local MySQL and Tomcat then simply deploy it to Jelastic and that's it - ready for the great unwashed masses. The fact that there is nothing special about the Jelastic environment is its greatest attribute in my opinion, I can deploy my .war file just about anywhere. Yippe :-) ....
Though he has run into a few problems (you can read more about those on his post), we are continuing to work through our beta and most of those issues should be resolved now.