The total number of available columns in Excel
Old Limit: 256  (2^8)
New Limit: 16k  (2^14)

The total number of available rows in Excel
Old Limit: 64k  (2^16)
New Limit: 1M  (2^20)

Total amount of PC memory that Excel can use
Old Limit: 1GB
New Limit: Maximum allowed by Windows

Number of unique colours allowed a single workbook
Old Limit: 56 (indexed colour)
New Limit: 4.3 billion (32-bit colour)

Number of conditional format conditions on a cell
Old Limit: 3 conditions
New Limit: Limited by available memory

Number of levels of sorting on a range or table
Old Limit: 3
New Limit: 64

Number of items shown in the Auto-Filter dropdown
Old Limit: 1,000
New Limit: 10,000

The total number of characters that can display in a cell
Old Limit: 1k (when the text is formatted)
New Limit: 32k or as many as will fit in the cell (regardless of formatting)

The number of characters per cell that Excel can print
Old Limit: 1k
New Limit: 32k

The total number of unique cell styles in a workbook (combinations of all cell formatting)
Old Limit: 4000
New Limit: 64k

The maximum length of formulas (in characters)
Old Limit: 1k characters
New Limit: 8k characters

The number of levels of nesting that Excel allows in formulas
Old Limit: 7
New Limit: 64

Maximum number of arguments to a function
Old Limit: 30
New Limit: 255

Maximum number of items found by “Find All”
Old Limit: ~64k (65472)
New Limit: ~2 Billion

Number of rows allowed in a Pivot Table
Old Limit: 64k
New Limit: 1M

Number of columns allowed in a Pivot Table
Old Limit: 255
New Limit: 16k

Maximum number of unique items within a single Pivot Field
Old Limit: 32k
New Limit: 1M

Length of the MDX name for a Pivot Table item; also the string length for a relational Pivot Table
Old Limit: 255 characters
New Limit: 32k

The length at which fields’ labels are truncated when added to PivotTable; this also includes caption length limitations
Old Limit: 255
New Limit: 32k

The number of fields (as seen in the field list) that a single PivotTable can have
Old Limit: 255
New Limit: 16k

The number of cells that may depend on a single area before Excel must do full calculations instead of partial calculations (because it can no longer track the dependencies required to do partial calculations)
Old Limit: 8k
New Limit: Limited by available memory

The number of different areas in a sheet that may have dependencies before Excel must do full calculations instead of partial calculations (because it can no longer track the dependencies required to do partial calculations)
Old Limit: 64k
New Limit: Limited by available memory

The number of array formulas in a worksheet that can refer to another (given) worksheet
Old Limit: 65k
New Limit: Limited by available memory

The number of categories that custom functions can be bucketed into
Old Limit: 32
New Limit: 255

The number of characters that may be updated in a non-resident external workbook reference
Old Limit: 255
New Limit: 32k

Number of rows of a column or columns that can be referred to in an array formula
Old Limit: 65,335
New Limit: Limitation removed (full-column references allowed)

The number of characters that can be stored and displayed in a cell formatted as Text
Old Limit: 255
New Limit: 32k