That's a very general question you are asking. Are there any particular weaknesses you have in mind? Without that, I can only give you the following general answer: combined with Facelets, MyFaces does deal very well with JSF 1.2 weaknesses. For example, the MyFaces Trinidad component set can help you to leverage AJAX functionality without the need for JSF 2.0. MyFaces Orchestra can create a conversation scope and manage persistence transactions for you; that's even more than JSF 2.0 has on offer. MyFaces ExtVal can help you to use Bean Validation (JSR 303) with JSF 2.0 and even goes beyond what JSF 2.0 implements as JSR 303 support. In my opinion, you can reach at least the same level as JSF 2.0 by using MyFaces and Facelets. That's one of the main themes in the MyFaces 1.2 Web Application Development book.
I hope this general answer is helpful. Don't hesitate to let me know if you have a particular JSF 1.2 weakness in mind.
I don't know what you mean exactly when referring to GET requests. Can you explain in a bit more details what downside of JSF you mean be referring to GET requests?
Regarding backing beans... AFAIK, there is no way to declare them by Annotation in JSF 1.2. However, you could use Spring to manage your beans instead of letting JSF manage them. If you're going to use Orchestra, you'll have to let Spring manage your beans anyway. The Orchestra chapter in the Apache MyFaces 1.2. Web Application Development book has a section on how to migrate managed beans from faces-config.xml to Springs application context.
Now I get what you mean. I don't see why using only POST requests would be a problem. In the projects I did, no one ever cared about whether we were using GET or POST requests. But that were all applications for internal use. For external applications, sometimes URLs and therefore the type of request do matter. I came across a project called PrettyFaces once. It says it enables you to use GET requests in JSF; I didn't try it myself, though. Perhaps you should give it a try...
PrettyFaces works very well. It's easy to install and use (especially if you build using Maven), And its author, Lincoln Baxter has been known to show up in this forum on occasion. I use PrettyFaces to provide me with "bookmarkable" URLs, although in one case they also helped be kludge around a blemish in Internet Explorer.
JSF2 adds a lot of support for direct URL (GET/POST) access, and I believe Lincoln helped to contribute to that effort.
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