Just to add a little from experience...
I agree with MJRBIM's comments as far as CE being primarily a report distribution tool, but one (not so small) thing to note is that your end users will be viewing them, perhaps, in a different viewer than the one you see when you use Crystal Reports. So, from the standpoint of data collection, formula calculation and most other logic aspects of the report, the reports will function the same (as MJRBIM stated, as long as you have the same data connection on CE as on the report). But when you use Crystal Reports to design the report, you are using, essentially, the ActiveX viewer to preview the report. CE offers several viewers, of which the ActiveX viewer is one option. So, if you're users view the reports distributed via CE with the ActiveX viewer, you shouldn't expect much difference in the reports visual behavior. But if, for example, they use the DHTML viewer, you might find that text boxes align, or are placed differently on the report than they do when the report is viewed in the ActiveX viewer. So, the issues you'll run into when viewing reports via CE are primarily display issues, not functionality issues.
By the way, you can control which viewer they use. It's just that in some instances you may be required to use a viewer other than the ActiveX viewer. For example, your users may include outside vendors who are not allowed to download ActiveX clients onto their pc's, so the DHTML viewer becomes their viewer of choice. So you then have to make sure your Crystal Reports looks good in the DHTML viewer.