There are a few MIDI sequencers listed at Sonic Spot. The list includes shareware, freeware and demos.
Anvil Studios has a freeware sequencer. (download page) Most of the features are enabled, but some are “optional extras” which you have to buy — like sight reading lessons for you MIDI instrument.
I’ve only used it for a few files, but it seems reliable. I mainly use MIDI for practice. It’s very useful, especially when I need to slow down a piece to play it. I also find it’s much more accurate than TAB.
On Anvil, the tempo box is on the right. If the MIDI file has tempo changes written into the score, then the version I have warns you that all such changes will be modified. Maybe there’s a more selective way to change tempos. I haven’t investigated enough.
If you want to see the score, click the view menu and select “composer”.