It's worth it, but you should know a couple of things before hand.
1.) The madcatz SE stick is fine, but the buttons really start to fail you after a few weeks of use (they'll get stuck, be unresponsive). You will have to order some sanwa replacements for around $15 and install them yourself (not that difficult, just a pain).
2.) You will suck if you've never used a stick before. It may take a few weeks to get used to it, and maybe even longer than that to return to the level you were at with the pad. This can frustrate some people. Just keep practicing motions in training, I wouldn't play online because you'll just piss yourself off.
After all that though, it really starts to pay off and you'll love it. I bought an SE and replaced the buttons and it works fine for me. The SE is cheap and it works well -- especially if you don't want to go all out on your first stick purchase.
However, I am now very tempted to upgrade to a TE or something =D