For the most part upgrading is an easy experience. Make sure you follow the tutorial (in the Tutorials section).
Note that it is not a one-to-one upgrade translation. If your site has been heavily customized using the legacy version you will need to spend some time reworking the new templates. Simple things like margin adjustments, link colors can easily be re-integrated into your site.
Note that some exhibit formats may not exist with version 2. Grow (the previous default) is now Visual Index. Thickbox does not exist but you can also use Visual Index as a replacement. There is a beta version of Slideshow in the forum if you search for it.
In some cases, your images may not appear after you upgrade - simply visit each exhibit via the studio and your images will be regenerated automatically.
And remember to link back to Indexhibit somewhere on your site.