It is not worse than AWS, but it is different. OpenStack is a collection of python programs that abstracts the physical hardware, such as cpu's, networking, storage and combines them to form a single interface over the top of the bare metal. Essentially you can turn many machines into an easy to use environment that looks like AWS.
In fact, all communication is done via web API's and there is even a compatibility API that speaks AWS. So if you have scripts that work with AWS, they will most likely work on OpenStack as well.
OpenStack is different in that not only can you choose an OpenStack provider, such as Rackspace, HP and others, but you can also run your own instance of OpenStack. All the software is released under the BSD 2 license. It can be a little tricky to get setup, but there are some projects out there to help get a working environment setup, DevStack in particular is very easy to use: http://devstack.org/
It really depends on what you're trying to do, as one is a product and the other is a service.
In terms of jumping in and getting started, AWS can be daunting, but it's not really that difficult to spin up an instance. OpenStack requires you to provision hardware and install a lot of different services, and architect how you want those services to be configured. It's not all that easy to get going (even with Juju, RDO, devstack, etc.). Both have a confusing array of names, so it's not always clear what part is what (ec2 vs nova, iam vs keystone, s3 vs swift/glance, ebs vs cinder, etc.), and not everything is fleshed out yet with OpenStack. I guess you could call it a work in progress. Actually, you could probably say the same with AWS, but it's much more mature.
OpenStack's biggest selling points at this point are that it's ultimately cheaper (in terms of opex) running your own cloud if you're at any kind of scale, but AWS saves you a lot up front (in terms of capex). OpenStack doesn't lock you in to a particular vendor and you can swap out parts like the hypervisor if you decide you want ESX or Xen over KVM. Unless you're using spot instances on EC2, AWS can be a lot more expensive (it would take only a few months to pay off a server if you're paying On Demand prices).
It's not worse, it's not better. It's got very different approach to many things. It also depends who deploys it and with which features/services enabled. Rackspace is different than HP cloud is different than ...
In comparison to AWS: The best thing in OS for me is the very flexible network configuration where you can define exactly what your environment looks like. The worst is lack of customised authorization / access control. Unless you need any specific part of AWS integrated into your environment, OS should give you most of the things you need. You can also mix&match services (just watch out where the internal data rates no longer apply).
In fact, all communication is done via web API's and there is even a compatibility API that speaks AWS. So if you have scripts that work with AWS, they will most likely work on OpenStack as well.
OpenStack is different in that not only can you choose an OpenStack provider, such as Rackspace, HP and others, but you can also run your own instance of OpenStack. All the software is released under the BSD 2 license. It can be a little tricky to get setup, but there are some projects out there to help get a working environment setup, DevStack in particular is very easy to use: http://devstack.org/