It is new version of OCS 2007. Most of end users can say that it is normal Instant Messaging software like MSN Messenger. Lync 2010 adds value your organizations in different angles. Yes you are right, this IM but more secure. Besides it has different features like audio / Video conferencing and connection your telephone system (Enterprise Voice). On the other hand, It is not free as MSN but Lync worth it.
I would like to talk about more specific details about Lync 2010. If you have one office and less than 50 clients, It does not suit your organization. You have more than one office and more than 100 clients and most of your clients are mobile, yes Lync is excellent solution for your organization. Your clients can talk each other free on Lync, You can schedule meeting on Exchange and mobile clients can attend your meeting on mobile their phones.
Training in organizations which have more branches is a nightmare these days. Because you have to teach your stuff and travel costs are really expensive and instructors sometimes need more than one day to train stuff, so accommodation cost will be added your costs. Instead of travelling, we can use Lync or familiar technologies for training.
Enterprise Voice is them most difficult subject of the features of Lync. If we want to use this feature, we should roll it out after IM and Conferencing implementation. The organizations which want to use Lync do not need telephone exchange any more after Lync 2010. Lync can work with your telephone exchange. Besides there are a lot of VOIP telephone machines that are compatible Lync 2010.
Training your end users must be in your roll out plan. There are plenty new features on Lync 2010 and we have to teach end users and helpdesk technicians.