Hi Friends,
This is Sidhanta Tripathy. I need to describe what are the limitation of Microsoft Infopath 2010 and some of the solution. First of all Why we need to create a content type in Microsoft infopath. The answer is in document library when we want to create a content type  and  put the infopath design there. In document library we can not retrieve the infopath form because the document library template may be different unlike the SharePoint 2010 list.

I want to narrate the some of the drawback and advantage of Microsoft Infopath Content Type.
1. If you have some site columns before in that site  with that existing name, Then the site column thus created will be grayed out. Hence they will not be liable to delete or editable.
2. Integer field are disabled. But you can take Decimal(Double) type.
3. At the creation of date type(Date Picker) field have no option(At the time of publish the form) to "Allow user to edit data in this field by using a datasheet" in infopath. That why it is grayed out. You can take Date and Time picker to represent date type field because it has a option "Allow user to edit data in this field by using a datasheet".
4. Attachment field can not created as columns as they are base64binary types. Therefore the attached file will not visible in edit/view mode
5. In case of Person and Group the column will be created for Display Name properties. By default the function selected for this field is First. It also provide other function such as Last,Count,Merge. If you will take group instead of Display Name it will by default take the function count mean it will show how much person has been entered in that Person and Group field. Person and Group become disabled/ grayed out as at the time of publishing or creation of field the option "Allow user to edit data in this field by using a datasheet" is not available. The Person and Group has 3 parts. a. Display Name  b. Account Id c. Account Name. They are stored in repeating table.
6. In case of Rich Text Box(Multiple Text Box) the otion "Allow user to edit data in this field by using a datasheet" is not available that's why this field is grayed out. You can take a text box and make it multiple text box so that the field will not be grayed out.
7. Dropdown Listbox will be editable site coloum as it has the option "Allow user to edit data in this field by using a datasheet".
8. Multiple selection listbox box will be disabled as it does not have the choice to check for the option "Allow user to edit data in this field by using a datasheet". While you are taking this field the first or default value will be updated to the list not the others.
9. The major advantage is you can create multiple content type from one infopath form.
10. If the site column of the infopath content type is disabled then it can not be recognized in workflow.
11. If you create a column at the time of publishing there will be a spacing between the capital letter and numeric. for example your field name is Name1 then when you will publish the form it will show you as Name 1. You can edit it according to your requirement.
12. If you will not choose the option "Allow user to edit data in this field by using a datasheet" , the site column thus created will be disabled.

Kindly Provides your valuable comments.