If this didn't integrate with Vegas I'd probably pass on the free offer, but part of that is a bit of wariness because while I was checking the full install, I got my 1st BSODs in what seems years. I quadruple checked everything to make sure it wasn't HitFilm, but, I'd be lying if I said there wasn't a nagging little voice bugging me to be careful with the software [I guess I'm just trying to explain that I might be unconsciously biased against it]. It might be useful for FX, & those FX *might* be a bit higher quality than some other lower cost software -- OTOH FX is where lower cost video software really puts a lot of emphasis, so you might rightly feel you have enough, &/or would rather spend your time & effort with a more generally capable editor.
IMHO the installation itself stinks -- Universal Extractor works with the .msi file download, so you can see the folder full of setup files for microsoft runtimes & such. Changed/added registry entries = ~600 in win7 64, but in a win7 64 VM they got over 100k, so mileage varies. HitFilm itself seems to only need 2 keys to run properly -- FXHome in HKCU\ Software & HKLM\ Software. The program's files are added to the FXhome folder in Program Files & the FXhome folder in ProgramData. There's a fair emphasis on DRM -- after the 1st BSOD I had to register again, & the dialog asked [said really] I'd have to de-activate the old install/registration.
The 2 things I don't like about HitFilm 2 Express are the lack of output options & the way it starts with more or less a web page ad filling the window. It's not the most intuitive video app I've used, but it lets you do minor editing & adds effects with enough settings available to make it useful. For output you have DV for avi files, & AVC/H.264. DV is not a lossless, or near lossless format for an intermediate to open in other software to finish editing &/or for a final encode -- AVC is for final delivery. DV will work, but files are huge, & you should be able to use a more lossless format without taking up much more storage space. HitFilm does offer an uncompressed format, but I'd suggest skipping it because of potential quality loss [because of color space conversions] & even bigger file sizes.